Ampholyte polymers and methods of treating subterranean formations with the same

ABSTRACT

Various embodiments disclosed relate to a composition including a crosslinkable ampholyte polymer or a crosslinked product of the same, methods of making and using the composition, and systems including the composition. In various embodiments, the present invention provides a method of treating a subterranean formation. The method can include obtaining or providing a composition including a crosslinkable ampholyte polymer. The crosslinkable ampholyte polymer can include an ethylene repeating unit including a —C(O)NH 2  group, an ethylene repeating unit including a —S(O) 2 OR 1  group, and an ethylene repeating unit comprising an —N + R 2   3 X −  group. At each occurrence, R 1  can be independently selected from the group consisting of —H and a counterion. At each occurrence, R 2  can be independently substituted or unsubstituted (C 1 -C 20 )hydrocarbyl. At each occurrence, X −  can be independently a counterion. The composition can also include at least one crosslinker. The method can include placing the composition in a subterranean formation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of and claims the benefit ofpriority under 35 U.S.C. §120 to U.S. Utility application Ser. No.13/929,835, filed Jun. 28, 2013, and to U.S. Utility application Ser.No. 13/929,871, filed Jun. 28, 2013, both of which claim the benefitunder 35 U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No.61/829,609 filed May 31, 2013, the disclosures of which are incorporatedherein in their entirety by reference.

BACKGROUND OF THE INVENTION

During the drilling, stimulation, completion, and production phases ofwells for petroleum or water extraction, the use of compositions havinghigh viscosities in subterranean formations is important for a widevariety of purposes. Higher viscosity fluids can more effectively carrymaterials to a desired location in a subterranean formation, such asproppants. The use of higher viscosity fluids during hydraulicfracturing generally results in larger more dominant fractures. Higherviscosity drilling fluids can more effectively carry materials away froma drilling location downhole.

One common way to attain high viscosities in drilling fluids is to use amixture of water and a viscosifier, such as guar gum. However, typicallyviscosifiers must be added in high concentrations to provide viscositiessufficient to suspend a desired proppant or to suspend drill cuttings,which can result in high transportation costs and low efficiencypreparation of viscous materials. However, pumping high viscositymaterials into a subterranean formation can require a large amount ofenergy. Also, the higher temperatures experienced in a subterraneanformation can limit, reduce, or degrade the effectiveness of certainviscosifiers, resulting in the use of larger amounts of viscosifiers tocompensate for the high temperatures, or the use of expensivetemperature-resistant viscosifiers. In addition, the presence of certainions in water can limit, reduce, or degrade the effectiveness of certainviscosifiers. This limits the use of certain ion-containing water, suchas sea water, or water recovered from or naturally produced by somesubterranean formations. As a result, the oil and gas industry spendssubstantial amounts of money and energy to use large amounts ofviscosifiers to compensate for salt sensitivity, obtain expensivesalt-resistant viscosifiers, obtain fresh water used for drilling fluidor fracturing fluid applications, or to avoid formations havingsubstantial concentrations of particular ions.

BRIEF DESCRIPTION OF THE FIGURES

The drawings illustrate generally, by way of example, but not by way oflimitation, various embodiments discussed in the present document.

FIG. 1 illustrates a drilling assembly, in accordance with variousembodiments.

FIG. 2 illustrates a system or apparatus for delivering a composition ina subterranean formation, in accordance with various embodiments.

FIG. 3 provides a graph of the viscosity of an ampholyte polymericcompound at various concentrations over time at an elevated temperature,in accordance with various embodiments.

FIG. 4 provides a graph comparing the viscosity of an ampholytepolymeric compound and a traditional viscosifier in water, in accordancewith various embodiments.

FIG. 5 provides a graph comparing the viscosity of an ampholytepolymeric compound and a traditional viscosifier in a high TDS water, inaccordance with various embodiments.

FIG. 6 provides a graph of percent friction reduction at varioussalinities for three friction reducing additives including one ampholytepolymeric compound, in accordance with various embodiments.

FIG. 7 provides a graph of viscosity measurements over time at varioustemperatures for a fluid including an ampholyte polymeric compound, inaccordance with various embodiments.

FIG. 8 provides a graph comparing the intrinsic viscosity over time fora fluid including an ampholyte polymeric compound and a fluid includinga traditional friction reducing agent, in accordance with variousembodiments.

FIG. 9 provides a graph of viscosity measurements over time at variousTDS concentrations for fluids including an ampholyte polymeric compound,in accordance with various embodiments.

FIG. 10 illustrates a photograph of a crosslinked ampholyte polymer, inaccordance with various embodiments.

FIG. 11 illustrates viscosity versus shear rate for a crosslinkedampholyte terpolymer, in accordance with various embodiments.

FIG. 12 illustrates frequency sweep data for various crosslinkedpolymers at 77° F., in accordance with various embodiments.

FIG. 13 illustrates frequency sweep data for various crosslinkedpolymers at 150° F., in accordance with various embodiments.

FIG. 14 illustrates a permeability profile for a crosslinkedpolyacrylamide, in accordance with various embodiments.

FIG. 15 illustrates a permeability profile for a crosslinked ampholyteterpolymer, in accordance with various embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to certain embodiments of thedisclosed subject matter, examples of which are illustrated in part inthe accompanying drawings. While the disclosed subject matter will bedescribed in conjunction with the enumerated claims, it will beunderstood that the exemplified subject matter is not intended to limitthe claims to the disclosed subject matter.

Values expressed in a range format should be interpreted in a flexiblemanner to include not only the numerical values explicitly recited asthe limits of the range, but also to include all the individualnumerical values or sub-ranges encompassed within that range as if eachnumerical value and sub-range is explicitly recited. For example, arange of “about 0.1% to about 5%” or “about 0.1% to 5%” should beinterpreted to include not just about 0.1% to about 5%, but also theindividual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g.,0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range.The statement “about X to Y” has the same meaning as “about X to aboutY,” unless indicated otherwise. Likewise, the statement “about X, Y, orabout Z” has the same meaning as “about X, about Y, or about Z,” unlessindicated otherwise.

In this document, the terms “a,” “an,” or “the” are used to include oneor more than one unless the context clearly dictates otherwise. The term“or” is used to refer to a nonexclusive “or” unless otherwise indicated.The statement “at least one of A and B” has the same meaning as “A, B,or A and B.” In addition, it is to be understood that the phraseology orterminology employed herein, and not otherwise defined, is for thepurpose of description only and not of limitation. Any use of sectionheadings is intended to aid reading of the document and is not to beinterpreted as limiting; information that is relevant to a sectionheading may occur within or outside of that particular section.Furthermore, all publications, patents, and patent documents referred toin this document are incorporated by reference herein in their entirety,as though individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated referenceshould be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In the methods of manufacturing described herein, the steps can becarried out in any order without departing from the principles of theinvention, except when a temporal or operational sequence is explicitlyrecited. Furthermore, specified steps can be carried out concurrentlyunless explicit claim language recites that they be carried outseparately. For example, a claimed step of doing X and a claimed step ofdoing Y can be conducted simultaneously within a single operation, andthe resulting process will fall within the literal scope of the claimedprocess.

Selected substituents within the compounds described herein are presentto a recursive degree. In this context, “recursive substituent” meansthat a substituent may recite another instance of itself or of anothersubstituent that itself recites the first substituent. Recursivesubstituents are an intended aspect of the disclosed subject matter.Because of the recursive nature of such substituents, theoretically, alarge number may be present in any given claim. One of ordinary skill inthe art of organic chemistry understands that the total number of suchsubstituents is reasonably limited by the desired properties of thecompound intended. Such properties include, by way of example and notlimitation, physical properties such as molecular weight, solubility,and practical properties such as ease of synthesis. Recursivesubstituents can call back on themselves any suitable number of times,such as about 1 time, about 2 times, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20,30, 50, 100, 200, 300, 400, 500, 750, 1000, 1500, 2000, 3000, 4000,5000, 10,000, 15,000, 20,000, 30,000, 50,000, 100,000, 200,000, 500,000,750,000, or about 1,000,000 times or more.

The term “about” as used herein can allow for a degree of variability ina value or range, for example, within 10%, within 5%, or within 1% of astated value or of a stated limit of a range.

The term “substantially” as used herein refers to a majority of, ormostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%,98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more.

The term “organic group” as used herein refers to but is not limited toany carbon-containing functional group. For example, anoxygen-containing group such as an alkoxy group, aryloxy group,aralkyloxy group, oxo(carbonyl) group, a carboxyl group including acarboxylic acid, carboxylate, and a carboxylate ester; asulfur-containing group such as an alkyl and aryl sulfide group; andother heteroatom-containing groups. Non-limiting examples of organicgroups include OR, OOR, OC(O)N(R)₂, CN, CF₃, OCF₃, R, C(O),methylenedioxy, ethylenedioxy, N(R)₂, SR, SOR, SO₂R, SO₂N(R)₂, SO₃R,C(O)R, C(O)C(O)R, C(O)CH₂C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R)₂,OC(O)N(R)₂, C(S)N(R)₂, (CH₂)₀₋₂N(R)C(O)R, (CH₂)₀₋₂N(R)N(R)₂,N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R)₂, N(R)SO₂R, N(R)SO₂N(R)₂,N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R)₂, N(R)C(S)N(R)₂,N(COR)COR, N(OR)R, C(═NH)N(R)₂, C(O)N(OR)R, or C(═NOR)R, wherein R canbe hydrogen (in examples that include other carbon atoms) or acarbon-based moiety, and wherein the carbon-based moiety can itself befurther substituted.

The term “substituted” as used herein refers to an organic group asdefined herein or molecule in which one or more hydrogen atoms containedtherein are replaced by one or more non-hydrogen atoms. The term“functional group” or “substituent” as used herein refers to a groupthat can be or is substituted onto a molecule or onto an organic group.Examples of substituents or functional groups include, but are notlimited to, a halogen (e.g., F, Cl, Br, and I); an oxygen atom in groupssuch as hydroxyl groups, alkoxy groups, aryloxy groups, aralkyloxygroups, oxo(carbonyl) groups, carboxyl groups including carboxylicacids, carboxylates, and carboxylate esters; a sulfur atom in groupssuch as thiol groups, alkyl and aryl sulfide groups, sulfoxide groups,sulfone groups, sulfonyl groups, and sulfonamide groups; a nitrogen atomin groups such as amines, hydroxylamines, nitriles, nitro groups,N-oxides, hydrazides, azides, and enamines; and other heteroatoms invarious other groups. Non-limiting examples of substituents J that canbe bonded to a substituted carbon (or other) atom include F, Cl, Br, I,OR, OC(O)N(R′)₂, CN, NO, NO₂, ONO₂, azido, CF₃, OCF₃, R, O (oxo), S(thiono), C(O), S(O), methylenedioxy, ethylenedioxy, N(R), SR, SOR,SO₂R, SO₂N(R)₂, SO₃R, C(O)R, C(O)C(O)R, C(O)CH₂C(O)R, C(S)R, C(O)OR,OC(O)R, C(O)N(R)₂, OC(O)N(R)₂, C(S)N(R)₂, (CH₂)₀₋₂N(R)C(O)R,(CH₂)₀₋₂N(R)N(R)₂, N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R)₂,N(R)SO₂R, N(R)SO₂N(R)₂, N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R)₂,N(R)C(S)N(R)₂, N(COR)COR, N(OR)R, C(═NH)N(R)₂, C(O)N(OR)R, or C(═NOR)R,wherein R can be hydrogen or a carbon-based moiety, and wherein thecarbon-based moiety can itself be further substituted; for example,wherein R can be hydrogen, alkyl, acyl, cycloalkyl, aryl, aralkyl,heterocyclyl, heteroaryl, or heteroarylalkyl, wherein any alkyl, acyl,cycloalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, or heteroarylalkylor R can be independently mono- or multi-substituted with J; or whereintwo R groups bonded to a nitrogen atom or to adjacent nitrogen atoms cantogether with the nitrogen atom or atoms form a heterocyclyl, which canbe mono- or independently multi-substituted with J.

The term “alkyl” as used herein refers to straight chain and branchedalkyl groups and cycloalkyl groups having from 1 to 40 carbon atoms, 1to about 20 carbon atoms, 1 to 12 carbons or, in some embodiments, from1 to 8 carbon atoms. Examples of straight chain alkyl groups includethose with from 1 to 8 carbon atoms such as methyl, ethyl, n-propyl,n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples ofbranched alkyl groups include, but are not limited to, isopropyl,iso-butyl, sec-butyl, t-butyl, neopentyl, isopentyl, and2,2-dimethylpropyl groups. As used herein, the term “alkyl” encompassesn-alkyl, isoalkyl, and anteisoalkyl groups as well as other branchedchain forms of alkyl. Representative substituted alkyl groups can besubstituted one or more times with any of the groups listed herein, forexample, amino, hydroxy, cyano, carboxy, nitro, thio, alkoxy, andhalogen groups.

The term “alkenyl” as used herein refers to straight and branched chainand cyclic alkyl groups as defined herein, except that at least onedouble bond exists between two carbon atoms. Thus, alkenyl groups havefrom 2 to 40 carbon atoms, or 2 to about 20 carbon atoms, or 2 to 12carbons or, in some embodiments, from 2 to 8 carbon atoms. Examplesinclude, but are not limited to vinyl, —CH═CH(CH₃), —CH═C(CH₃)₂,—C(CH₃)═CH₂, —C(CH₃)═CH(CH₃), —C(CH₂CH₃)═CH₂, cyclohexenyl,cyclopentenyl, cyclohexadienyl, butadienyl, pentadienyl, and hexadienylamong others.

The term “alkynyl” as used herein refers to straight and branched chainalkyl groups, except that at least one triple bond exists between twocarbon atoms. Thus, alkynyl groups have from 2 to 40 carbon atoms, 2 toabout 20 carbon atoms, or from 2 to 12 carbons or, in some embodiments,from 2 to 8 carbon atoms. Examples include, but are not limited to—C≡CH, —C≡C(CH₃), —C≡C(CH₂CH₃), —CH₂C≡CH, —CH₂C≡C(CH₃), and—CH₂C≡C(CH₂CH₃) among others.

The term “acyl” as used herein refers to a group containing a carbonylmoiety wherein the group is bonded via the carbonyl carbon atom. Thecarbonyl carbon atom is also bonded to another carbon atom, which can bepart of an alkyl, aryl, aralkyl cycloalkyl, cycloalkylalkyl,heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl group orthe like. In the special case wherein the carbonyl carbon atom is bondedto a hydrogen, the group is a “formyl” group, an acyl group as the termis defined herein. An acyl group can include 0 to about 12-20 or 12-40additional carbon atoms bonded to the carbonyl group. An acyl group caninclude double or triple bonds within the meaning herein. An acryloylgroup is an example of an acyl group. An acyl group can also includeheteroatoms within the meaning here. A nicotinoyl group(pyridyl-3-carbonyl) is an example of an acyl group within the meaningherein. Other examples include acetyl, benzoyl, phenylacetyl,pyridylacetyl, cinnamoyl, and acryloyl groups and the like. When thegroup containing the carbon atom that is bonded to the carbonyl carbonatom contains a halogen, the group is termed a “haloacyl” group. Anexample is a trifluoroacetyl group.

The term “aryl” as used herein refers to cyclic aromatic hydrocarbonsthat do not contain heteroatoms in the ring. Thus aryl groups include,but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl,indacenyl, fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl,naphthacenyl, chrysenyl, biphenylenyl, anthracenyl, and naphthyl groups.In some embodiments, aryl groups contain about 6 to about 14 carbons inthe ring portions of the groups. Aryl groups can be unsubstituted orsubstituted, as defined herein. Representative substituted aryl groupscan be mono-substituted or substituted more than once, such as, but notlimited to, 2-, 3-, 4-, 5-, or 6-substituted phenyl or 2-8 substitutednaphthyl groups, which can be substituted with carbon or non-carbongroups such as those listed herein.

The term “heterocyclyl” as used herein refers to aromatic andnon-aromatic ring compounds containing 3 or more ring members, of whichone or more is a heteroatom such as, but not limited to, N, O, and S.Thus, a heterocyclyl can be a cycloheteroalkyl, or a heteroaryl, or ifpolycyclic, any combination thereof. In some embodiments, heterocyclylgroups include 3 to about 20 ring members, whereas other such groupshave 3 to about 15 ring members. A heterocyclyl group designated as aC₂-heterocyclyl can be a 5-ring with two carbon atoms and threeheteroatoms, a 6-ring with two carbon atoms and four heteroatoms and soforth. Likewise a C₄-heterocyclyl can be a 5-ring with one heteroatom, a6-ring with two heteroatoms, and so forth. The number of carbon atomsplus the number of heteroatoms equals the total number of ring atoms. Aheterocyclyl ring can also include one or more double bonds. Aheteroaryl ring is an embodiment of a heterocyclyl group. The phrase“heterocyclyl group” includes fused ring species including those thatinclude fused aromatic and non-aromatic groups.

The term “alkoxy” as used herein refers to an oxygen atom connected toan alkyl group, including a cycloalkyl group, as are defined herein.Examples of linear alkoxy groups include but are not limited to methoxy,ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, and the like. Examples ofbranched alkoxy include but are not limited to isopropoxy, sec-butoxy,tert-butoxy, isopentyloxy, isohexyloxy, and the like. Examples of cyclicalkoxy include but are not limited to cyclopropyloxy, cyclobutyloxy,cyclopentyloxy, cyclohexyloxy, and the like. An alkoxy group can includeone to about 12-20 or about 12-40 carbon atoms bonded to the oxygenatom, and can further include double or triple bonds, and can alsoinclude heteroatoms. For example, an allyloxy group is an alkoxy groupwithin the meaning herein. A methoxyethoxy group is also an alkoxy groupwithin the meaning herein, as is a methylenedioxy group in a contextwhere two adjacent atoms of a structure are substituted therewith.

The term “amine” as used herein refers to primary, secondary, andtertiary amines having, e.g., the formula N(group)₃ wherein each groupcan independently be H or non-H, such as alkyl, aryl, and the like.Amines include but are not limited to R—NH₂, for example, alkylamines,arylamines, alkylarylamines; R₂NH wherein each R is independentlyselected, such as dialkylamines, diarylamines, aralkylamines,heterocyclylamines and the like; and R₃N wherein each R is independentlyselected, such as trialkylamines, dialkylarylamines, alkyldiarylamines,triarylamines, and the like. The term “amine” also includes ammoniumions as used herein.

The term “amino group” as used herein refers to a substituent of theform —NH₂, —NHR, —NR₂, —NR₃ ⁺, wherein each R is independently selected,and protonated forms of each, except for —NR₃ ⁺, which cannot beprotonated. Accordingly, any compound substituted with an amino groupcan be viewed as an amine. An “amino group” within the meaning hereincan be a primary, secondary, tertiary, or quaternary amino group. An“alkylamino” group includes a monoalkylamino, dialkylamino, andtrialkylamino group.

The terms “halo,” “halogen,” or “halide” group, as used herein, bythemselves or as part of another substituent, mean, unless otherwisestated, a fluorine, chlorine, bromine, or iodine atom.

The term “haloalkyl” group, as used herein, includes mono-halo alkylgroups, poly-halo alkyl groups wherein all halo atoms can be the same ordifferent, and per-halo alkyl groups, wherein all hydrogen atoms arereplaced by halogen atoms, such as fluoro. Examples of haloalkyl includetrifluoromethyl, 1,1-dichloroethyl, 1,2-dichloroethyl,1,3-dibromo-3,3-difluoropropyl, perfluorobutyl, and the like.

The term “hydrocarbon” as used herein refers to a functional group ormolecule that includes carbon and hydrogen atoms. The term can alsorefer to a functional group or molecule that normally includes bothcarbon and hydrogen atoms but wherein all the hydrogen atoms aresubstituted with other functional groups.

As used herein, the term “hydrocarbyl” refers to a functional groupderived from a straight chain, branched, or cyclic hydrocarbon, and canbe alkyl, alkenyl, alkynyl, aryl, cycloalkyl, acyl, or any combinationthereof.

The term “solvent” as used herein refers to a liquid that can dissolve asolid, liquid, or gas. Nonlimiting examples of solvents are silicones,organic compounds, water, alcohols, ionic liquids, and supercriticalfluids.

The term “number-average molecular weight” as used herein refers to theordinary arithmetic mean of the molecular weight of individual moleculesin a sample. It is defined as the total weight of all molecules in asample divided by the total number of molecules in the sample.Experimentally, the number-average molecular weight (M_(n)) isdetermined by analyzing a sample divided into molecular weight fractionsof species i having n_(i) molecules of molecular weight M_(i) throughthe formula M_(n)=ΣM_(i)n_(i)/Σn_(i). The number-average molecularweight can be measured by a variety of well-known methods including gelpermeation chromatography, spectroscopic end group analysis, andosmometry. If unspecified, molecular weights of polymers given hereinare number-average molecular weights.

The term “weight-average molecular weight” as used herein refers toM_(w), which is equal to ΣM_(i) ²n_(i)/ΣM_(i)n_(i), where n_(i) is thenumber of molecules of molecular weight M_(i). In various examples, theweight-average molecular weight can be determined using lightscattering, small angle neutron scattering, X-ray scattering, andsedimentation velocity.

The term “room temperature” as used herein refers to a temperature ofabout 15° C. to 28° C.

The term “standard temperature and pressure” as used herein refers to20° C. and 101 kPa.

As used herein, “degree of polymerization” is the number of repeatingunits in a polymer.

As used herein, the term “polymer” refers to a molecule having at leastone repeating unit and can include copolymers.

The term “copolymer” as used herein refers to a polymer that includes atleast two different monomers. A copolymer can include any suitablenumber of monomers.

The term “downhole” as used herein refers to under the surface of theearth, such as a location within or fluidly connected to a wellbore.

As used herein, the term “drilling fluid” refers to fluids, slurries, ormuds used in drilling operations downhole, such as during the formationof the wellbore.

As used herein, the term “stimulation fluid” refers to fluids orslurries used downhole during stimulation activities of the well thatcan increase the production of a well, including perforation activities.In some examples, a stimulation fluid can include a fracturing fluid oran acidizing fluid.

As used herein, the term “clean-up fluid” refers to fluids or slurriesused downhole during clean-up activities of the well, such as anytreatment to remove material obstructing the flow of desired materialfrom the subterranean formation. In one example, a clean-up fluid can bean acidification treatment to remove material formed by one or moreperforation treatments. In another example, a clean-up fluid can be usedto remove a filter cake.

As used herein, the term “fracturing fluid” refers to fluids or slurriesused downhole during fracturing operations.

As used herein, the term “spotting fluid” refers to fluids or slurriesused downhole during spotting operations, and can be any fluid designedfor localized treatment of a downhole region. In one example, a spottingfluid can include a lost circulation material for treatment of aspecific section of the wellbore, such as to seal off fractures in thewellbore and prevent sag. In another example, a spotting fluid caninclude a water control material. In some examples, a spotting fluid canbe designed to free a stuck piece of drilling or extraction equipment,can reduce torque and drag with drilling lubricants, preventdifferential sticking, promote wellbore stability, and can help tocontrol mud weight.

As used herein, the term “completion fluid” refers to fluids or slurriesused downhole during the completion phase of a well, including cementingcompositions.

As used herein, the term “remedial treatment fluid” refers to fluids orslurries used downhole for remedial treatment of a well. Remedialtreatments can include treatments designed to increase or maintain theproduction rate of a well, such as stimulation or clean-up treatments.

As used herein, the term “abandonment fluid” refers to fluids orslurries used downhole during or preceding the abandonment phase of awell.

As used herein, the term “acidizing fluid” refers to fluids or slurriesused downhole during acidizing treatments. In one example, an acidizingfluid is used in a clean-up operation to remove material obstructing theflow of desired material, such as material formed during a perforationoperation. In some examples, an acidizing fluid can be used for damageremoval.

As used herein, the term “cementing fluid” refers to fluids or slurriesused during cementing operations of a well. For example, a cementingfluid can include an aqueous mixture including at least one of cementand cement kiln dust. In another example, a cementing fluid can includea curable resinous material such as a polymer that is in an at leastpartially uncured state.

As used herein, the term “water control material” refers to a solid orliquid material that interacts with aqueous material downhole, such thathydrophobic material can more easily travel to the surface and such thathydrophilic material (including water) can less easily travel to thesurface. A water control material can be used to treat a well to causethe proportion of water produced to decrease and to cause the proportionof hydrocarbons produced to increase, such as by selectively bindingtogether material between water-producing subterranean formations andthe wellbore while still allowing hydrocarbon-producing formations tomaintain output.

As used herein, the term “packing fluid” refers to fluids or slurriesthat can be placed in the annular region of a well between tubing andouter casing above a packer. In various examples, the packing fluid canprovide hydrostatic pressure in order to lower differential pressureacross the sealing element, lower differential pressure on the wellboreand casing to prevent collapse, and protect metals and elastomers fromcorrosion.

As used herein, the term “fluid” refers to liquids and gels, unlessotherwise indicated.

As used herein, the term “subterranean material” or “subterraneanformation” refers to any material under the surface of the earth,including under the surface of the bottom of the ocean. For example, asubterranean formation or material can be any section of a wellbore andany section of a subterranean petroleum- or water-producing formation orregion in fluid contact with the wellbore. Placing a material in asubterranean formation can include contacting the material with anysection of a wellbore or with any subterranean region in fluid contacttherewith. Subterranean materials can include any materials placed intothe wellbore such as cement, drill shafts, liners, tubing, or screens;placing a material in a subterranean formation can include contactingwith such subterranean materials. In some examples, a subterraneanformation or material can be any below-ground region that can produceliquid or gaseous petroleum materials, water, or any sectionbelow-ground in fluid contact therewith. For example, a subterraneanformation or material can be at least one of an area desired to befractured, a fracture or an area surrounding a fracture, and a flowpathway or an area surrounding a flow pathway, wherein a fracture or aflow pathway can be optionally fluidly connected to a subterraneanpetroleum- or water-producing region, directly or through one or morefractures or flow pathways.

As used herein, “treatment of a subterranean formation” can include anyactivity directed to extraction of water or petroleum materials from asubterranean petroleum- or water-producing formation or region, forexample, including drilling, stimulation, hydraulic fracturing,clean-up, acidizing, completion, cementing, remedial treatment,abandonment, and the like.

As used herein, a “flow pathway” downhole can include any suitablesubterranean flow pathway through which two subterranean locations arein fluid connection. The flow pathway can be sufficient for petroleum orwater to flow from one subterranean location to the wellbore, orvice-versa. A flow pathway can include at least one of a hydraulicfracture, a fluid connection across a screen, across gravel pack, acrossproppant, including across resin-bonded proppant or proppant depositedin a fracture, and across sand. A flow pathway can include a naturalsubterranean passageway through which fluids can flow. In someembodiments, a flow pathway can be a water source and can include water.In some embodiments, a flow pathway can be a petroleum source and caninclude petroleum. In some embodiments, a flow pathway can be sufficientto divert from a wellbore, fracture, or flow pathway connected theretoat least one of water, a downhole fluid, or a produced hydrocarbon.

As used herein “gpt” refers to gallons per thousand gallons.

In various embodiments, the present invention provides a method oftreating a subterranean formation. The method includes obtaining orproviding a composition including a crosslinkable ampholyte polymer. Thecrosslinkable ampholyte polymer includes an ethylene repeating unitincluding a —C(O)NH₂ group, an ethylene repeating unit including an—S(O)₂OR¹ group, and an ethylene repeating unit including an —N⁺R² ₃X⁻group. At each occurrence, R¹ is independently selected from the groupconsisting of —H and a counterion. At each occurrence, R² isindependently substituted or unsubstituted (C₁-C₂₀)hydrocarbyl. At eachoccurrence, X⁻ is independently a counterion. The composition includesat least one crosslinker. The method includes placing the composition ina subterranean formation.

In various embodiments, the present invention provides a method oftreating a subterranean formation. The method includes obtaining orproviding a composition. The composition includes a reaction product ofa mixture. The mixture includes a crosslinkable ampholyte polymerincluding an ethylene repeating unit including a —C(O)NH₂ group, anethylene repeating unit including an —S(O)₂OR¹ group, and an ethylenerepeating unit including an —N⁺R² ₃X⁻ group. At each occurrence, R¹ isindependently selected from the group consisting of —H and a counterion.At each occurrence, R² is independently substituted or unsubstituted(C₁-C₂₀)hydrocarbyl. At each occurrence, X⁻ is independently acounterion. The mixture also includes at least one crosslinker. Themethod also includes placing the composition in a subterraneanformation.

In various embodiments, the present invention provides a method oftreating a subterranean formation. The method includes obtaining orproviding a composition including a crosslinkable ampholyte polymer. Thecrosslinkable ampholyte polymer includes repeating units having thestructure:

At each occurrence, R¹ is independently selected from the groupconsisting of —H and a counterion. The repeating units are in a block,alternate, or random configuration, and each repeating unit isindependently in the orientation shown or in the opposite orientation.The crosslinkable ampholyte polymer has a molecular weight of about100,000 g/mol to about 20,000,000 g/mol. The crosslinkable ampholytepolymer has about 30 wt % to about 50 wt % of the ethylene repeatingunit including the —C(O)NH₂ group, about 5 wt % to about 15 wt % of theethylene repeating unit including the —S(O)₂OR¹ group, and about 40 wt %to about 60 wt % of the ethylene repeating unit including the —N⁺R² ₃X⁻group. The composition also includes a crosslinker includingpolyethyleneimine. The composition also includes a downhole fluidincluding at least one of a drilling fluid, a fracturing fluid, adiverting fluid, and a lost circulation treatment fluid. The method alsoincludes placing the composition in a subterranean formation. About0.001 wt % to about 30 v/v % of the composition is the crosslinkableampholyte polymer and the crosslinker.

In various embodiments, the present invention provides a system. Thesystem includes a composition including a crosslinkable ampholytepolymer. The crosslinkable ampholyte polymer has about Z^(wt) wt % of anethylene repeating unit including the —C(O)NH₂ group, about N^(wt) wt %of an ethylene repeating unit including a —S(O)₂OR¹ group, and aboutM^(wt) wt % of an ethylene repeating unit including an —N⁺R² ₃X⁻ group.At each occurrence R¹ is independently selected from the groupconsisting of —H and a counterion. At each occurrence, R² isindependently substituted or unsubstituted (C₁-C₂₀)hydrocarbyl. At eachoccurrence, X⁻ is independently a counterion. The repeating units are inblock, alternate, or random configuration. The variable Z^(wt) is about10% to about 70%, N^(wt) is about 1% to about 40%, and M^(wt) is about20% to about 80%. The crosslinkable ampholyte polymer has a molecularweight of about 100,000 g/mol to about 20,000,000 g/mol. The compositionalso includes at least one crosslinker. The system also includes asubterranean formation including the composition therein.

In various embodiments, the present invention provides a composition fortreatment of a subterranean formation. The composition includes acrosslinkable ampholyte polymer having about Z^(wt) wt % of an ethylenerepeating unit including the —C(O)NH₂ group, about N^(wt) wt % of anethylene repeating unit including a —S(O)₂OR¹ group, and about M^(wt) wt% of an ethylene repeating unit including an —N⁺R² ₃X⁻ group. At eachoccurrence R¹ is independently selected from the group consisting of —Hand a counterion. At each occurrence, R² is independently substituted orunsubstituted (C₁-C₂₀)hydrocarbyl. At each occurrence, X⁻ isindependently a counterion. The repeating units are in block, alternate,or random configuration. The variable Z^(wt) is about 10% to about 70%,N^(wt) is about 1% to about 40%, and M^(wt) is about 20% to about 80%.The crosslinkable ampholyte polymer has a molecular weight of about100,000 g/mol to about 20,000,000 g/mol. The composition includes atleast one crosslinker. The composition also includes a downhole fluid.

In various embodiments, the present invention provides a composition fortreatment of a subterranean formation. The composition includes areaction product of a mixture. The mixture includes a crosslinkableampholyte polymer having about Z^(wt) wt % of an ethylene repeating unitincluding the —C(O)NH₂ group, about N^(wt) wt % of an ethylene repeatingunit including a —S(O)₂OR¹ group, and about M^(wt) wt % of an ethylenerepeating unit including an —N⁺R² ₃X⁻ group. At each occurrence R¹ isindependently selected from the group consisting of —H and a counterion.At each occurrence, R² is independently substituted or unsubstituted(C₁-C₂₀)hydrocarbyl. At each occurrence, X⁻ is independently acounterion. The repeating units are in block, alternate, or randomconfiguration. The variable Z^(wt) is about 10% to about 70%, N^(wt) isabout 1% to about 40%, and M^(wt) is about 20% to about 80%. Thecrosslinkable ampholyte polymer has a molecular weight of about 100,000g/mol to about 20,000,000 g/mol. The mixture also includes at least onecrosslinker. The composition also includes a downhole fluid.

In various embodiments, the present invention provides a composition fortreatment of a subterranean formation. The composition includes acrosslinkable ampholyte polymer including repeating units having thestructure:

At each occurrence R¹ is independently selected from the groupconsisting of —H and a counterion. The repeating units are in a block,alternate, or random configuration, and each repeating unit isindependently in the orientation shown or in the opposite orientation.The crosslinkable ampholyte polymer has a molecular weight of about100,000 g/mol to about 20,000,000 g/mol. The crosslinkable ampholytepolymer has about 30 wt % to about 50 wt % of the ethylene repeatingunit including the —C(O)NH₂ group, about 5 wt % to about 15 wt % of theethylene repeating unit including the —S(O)₂OR¹ group, and about 40 wt %to about 60 wt % of the ethylene repeating unit including the —N⁺R² ₃X⁻group. The composition includes a crosslinker includingpolyethyleneimine. The composition also includes a downhole fluidincluding at least one of a drilling fluid, a fracturing fluid, adiverting fluid, and a lost circulation treatment fluid. About 0.001 wt% to about 30 v/v % of the composition is the crosslinkable ampholytepolymer and the crosslinker.

In various embodiments, the present invention provides a method ofpreparing a composition for treatment of a subterranean formation. Themethod includes forming a composition including a crosslinkableampholyte polymer including an ethylene repeating unit including a—C(O)NH₂ group, an ethylene repeating unit including an —S(O)₂OR¹ group,and an ethylene repeating unit including an —N⁺R² ₃X⁻ group. At eachoccurrence, R¹ is independently selected from the group consisting of —Hand a counterion. At each occurrence, R² is independently substituted orunsubstituted (C₁-C₂₀)hydrocarbyl. At each occurrence, X⁻ isindependently a counterion. The composition also includes at least onecrosslinker.

Various embodiments of the present invention provide certain advantagesover other compositions including viscosifiers and methods of using thesame, at least some of which are unexpected. For example, in someembodiments, the uncrosslinked crosslinkable ampholyte polymer can actas a friction reducer before crosslinking (e.g., for slickwaterfracturing or other uses), and can act as a viscosifier aftercrosslinking. In some embodiments, the uncrosslinked crosslinkableampholyte polymer can act as a viscosifier before crosslinking, and canprovide an even greater viscosity increase or even a solidificationafter crosslinking. In some embodiments, the ability of thecrosslinkable ampholyte polymer to provide multiple uses in addition toviscosification or gelation in a subterranean formation, such asfriction reduction and viscosification, can at least one of: simplify asubterranean operation, reduce transportation costs, reduce the costs ofstoring and blending multiple materials at a worksite, reduce the amountof equipment needed at a worksite (e.g., reduce footprint), and reducethe equipment cost overall.

In some embodiments, the crosslinkable ampholyte polymer can provide agreater increase in viscosity of a downhole fluid per mass (e.g., via atleast partially crosslinking the crosslinkable ampholyte polymer) thanother viscosifiers. Compared to the viscosity of a downhole fluid havinga given concentration of a viscosifier (or, e.g., a downhole fluidformed by at least partially crosslinking a given concentration of aviscosifier), a corresponding downhole fluid having the same or lowerconcentration of various embodiments of the crosslinkable ampholytepolymer (or, e.g., formed by at least partially crosslinking thecrosslinkable ampholyte polymer) can have a higher viscosity. In someembodiments, by enabling a higher viscosity with the use of lessviscosifier, the crosslinkable ampholyte polymer can provide lowertransportation costs and shorter preparation time, making operationsmore efficient overall.

In various embodiments, the crosslinkable ampholyte polymer can be lessexpensive per unit mass as compared to conventional viscosifiers. Invarious embodiments, the crosslinkable ampholyte polymer can provide agreater viscosity increase or a higher gel strength per unit cost ascompared to other viscosifiers. In various embodiments, thecrosslinkable ampholyte polymer can provide a greater viscosity increaseor a higher gel strength per unit cost in the presence of various saltsor under high temperature conditions, as compared to other viscosifiers.

Conventional viscosifiers provide viscosification of a compositionbefore and during transport to a desired location in a subterraneanformation, requiring the energy-intensive pumping of a high viscositycomposition through tubular conduits to reach the desired location inthe subterranean formation. In various embodiments, the crosslinkableampholyte polymer partially or fully avoids providing a viscosityincrease until the composition reaches or becomes near a desiredsubterranean location, and in some embodiments provides a reduction infriction en route to the desired location. In various embodiments, theviscosity increase provided by the crosslinkable ampholyte polymer canbe triggered by heat, such as the higher temperature of the desiredlocation in a subterranean formation. In various embodiments, bydelaying the viscosity increase, the crosslinkable ampholyte polymer canprovide a more efficient method of providing high viscosity compositionsto a desired location in a subterranean formation. In some embodiments,the crosslinkable ampholyte polymer can be optimized for use at aparticular temperature by varying the structure or concentration of atleast one of the viscosifier and the crosslinker to provide a desiredviscosity in a desired location.

Many conventional viscosifiers suffer a decrease in the viscosity or gelstrength provided when used under high temperature conditions such asthe conditions found in many subterranean formations. In someembodiments, under high temperature conditions, the crosslinkableampholyte polymer can provide a higher viscosity or higher gel strength,or can provide less or no decrease in viscosity or gel strength, ascompared to the viscosity provided by other conventional viscosifiersunder corresponding conditions. In various embodiments, the highertemperature stability of the crosslinkable ampholyte polymer can allow adesired level of viscosification or gelation with the use of lessviscosifier, or can allow a higher viscosity or gel strength to beachieved in a subterranean formation, as compared to other conventionalviscosifiers, thereby providing a more versatile, more cost effective,or more efficient viscosification or gelation in the subterraneanformation than other methods and compositions.

Many conventional viscosifiers suffer a decrease in the viscosity or gelstrength provided when used with liquids such as water having certainions present at particular concentrations. For example, manyviscosifiers suffer a decrease in the viscosity or gel strength providedwhen used with liquids having certain amounts of salts dissolved thereinsuch as sodium chloride or potassium chloride. In some embodiments, thecrosslinkable ampholyte polymer can be used with liquids having ionsdissolved therein and can suffer less or no negative effects from theions, as compared to conventional methods and compositions for use insubterranean formations, such as less or no decrease in the viscosityprovided. By being able to retain the viscosity or gel strength providedor suffer less reduction in viscosity or gel strength in the presence ofvarious ions or in the presence of larger amounts of particular ionsthan other methods and compositions, various embodiments can avoid theneed for ion-free or ion-depleted water, or can avoid a need to addgreater amounts of viscosifier to achieve a desired effect in asubterranean formation, and can thereby be more versatile, more costeffective, or more efficient than other methods and compositions forsubterranean use.

In various embodiments, by providing a higher viscosity or higher gelstrength under high temperature conditions or high salinity conditions,the crosslinkable ampholyte polymer can provide a more effectivesubterranean or downhole fluid, such as a more effective drilling fluidthat has greater cutting carrying capacity, sag resistance, orequivalent circulating density, a more effective hydraulic fracturingfluid that can more effectively carry proppant or form more dominantfractures, or a more effective diverter or lost circulation materialthat more effectively seals off flow pathways or controls permeability.In various embodiments, by providing a higher viscosity or gel strengthunder high temperature conditions or high salinity conditions, thecrosslinkable ampholyte polymer can provide a more effective sweepingagent (e.g., for removing cuttings from the wellbore), improvedequivalent circulating density management, and improved fluid losscontrol (e.g., the higher viscosity can reduce fluid flow in porespaces).

Method of Treating a Subterranean Formation.

In various embodiments, the present invention provides a method oftreating a subterranean formation. In some embodiments, the methodincludes obtaining or providing a composition including a crosslinkerand a crosslinkable ampholyte polymer including an ethylene repeatingunit including a —C(O)NH₂ group, an ethylene repeating unit including an—S(O)₂OR¹ group, and an ethylene repeating unit including an —N⁺R² ₃X⁻group. At each occurrence, R¹ can be independently selected from thegroup consisting of —H and a counterion. At each occurrence, R² can beindependently substituted or unsubstituted (C₁-C₂₀)hydrocarbyl, and ateach occurrence, X⁻ can be independently a counterion. In someembodiments, the method includes obtaining or providing a compositionincluding a reaction product of a crosslinker and the crosslinkableampholyte polymer (e.g., a product of a crosslinking reaction betweenthe crosslinker and the crosslinkable ampholyte polymer). The obtainingor providing of the composition can occur at any suitable time and atany suitable location. The obtaining or providing of the composition canoccur above the surface. The obtaining or providing of the compositioncan occur in the subterranean formation (e.g., downhole). The methodalso includes placing the composition in a subterranean formation. Theplacing of the composition in the subterranean formation can includecontacting the composition and any suitable part of the subterraneanformation, or contacting the composition and a subterranean material,such as any suitable subterranean material. The subterranean formationcan be any suitable subterranean formation. In some embodiments, themethod is a method of drilling the subterranean formation. In someembodiments, the method is a method of fracturing the subterraneanformation. For example, the composition can be used as or with adrilling fluid, a hydraulic fracturing fluid, a diverting fluid, and alost circulation treatment fluid.

In some examples, the placing of the composition in the subterraneanformation (e.g., downhole) includes contacting the composition with orplacing the composition in at least one of a fracture, at least a partof an area surrounding a fracture, a flow pathway, an area surrounding aflow pathway, and an area desired to be fractured. The placing of thecomposition in the subterranean formation can be any suitable placingand can include any suitable contacting between the subterraneanformation and the composition. The placing of the composition in thesubterranean formation can include at least partially depositing thecomposition in a fracture, flow pathway, or area surrounding the same.

The method can include hydraulic fracturing, such as a method ofhydraulic fracturing to generate a fracture or flow pathway. The placingof the composition in the subterranean formation or the contacting ofthe subterranean formation and the hydraulic fracturing can occur at anytime with respect to one another; for example, the hydraulic fracturingcan occur at least one of before, during, and after the contacting orplacing. In some embodiments, the contacting or placing occurs duringthe hydraulic fracturing, such as during any suitable stage of thehydraulic fracturing, such as during at least one of a pre-pad stage(e.g., during injection of water with no proppant, and additionallyoptionally mid- to low-strength acid), a pad stage (e.g., duringinjection of fluid only with no proppant, with some viscosifier, such asto begin to break into an area and initiate fractures to producesufficient penetration and width to allow proppant-laden later stages toenter), or a slurry stage of the fracturing (e.g., viscous fluid withproppant). The method can include performing a stimulation treatment atleast one of before, during, and after placing the composition in thesubterranean formation in the fracture, flow pathway, or areasurrounding the same. The stimulation treatment can be, for example, atleast one of perforating, acidizing, injecting of cleaning fluids,propellant stimulation, and hydraulic fracturing. In some embodiments,the stimulation treatment at least partially generates a fracture orflow pathway where the composition is placed or contacted, or thecomposition is placed or contacted to an area surrounding the generatedfracture or flow pathway.

The method can include diverting or fluid loss control. The compositioncan be delivered to the subterranean formation to a flowpath causingfluid loss or undesired introduction of water. The composition can becrosslinked, such that the flowpath is at least partially sealed by thereaction product of the ampholyte polymer and the crosslinker, at leastpartially stopping fluid loss or preventing water from entering thewellbore and contaminating fluids such as production fluids.

In some embodiments, in addition to the crosslinkable ampholyte polymerand the crosslinker, or a reaction product thereof, the composition caninclude an aqueous liquid. The method can further include mixing theaqueous liquid with the polymer viscosifier. The mixing can occur at anysuitable time and at any suitable location, such as above surface or inthe subterranean formation. The aqueous liquid can be any suitableaqueous liquid, such as at least one of water, brine, produced water,flowback water, brackish water, and sea water. In some embodiments, theaqueous liquid can include at least one of an aqueous drilling fluid,aqueous fracturing fluid, aqueous diverting fluid, and an aqueous fluidloss control fluid. In some embodiments, the aqueous liquid can be theaqueous phase of an emulsion (e.g., the composition can include anemulsion having as the aqueous phase the aqueous liquid).

The composition can include any suitable proportion of the aqueousliquid, such that the composition can be used as described herein. Forexample, about 0.000,1 wt % to 99.999,9 wt % of the composition can bethe aqueous liquid, or about 0.01 wt % to about 99.99 wt %, about 0.1 wt% to about 99.9 wt %, or about 20 wt % to about 90 wt %, or about0.000,1 wt % or less, or about 0.000,001 wt %, 0.000,1, 0.001, 0.01,0.1, 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92,93, 94, 95, 96, 97, 98, 99, 99.9, 99.99, 99.999 wt %, or about 99.999,9wt % or more of the composition can be the aqueous liquid.

The aqueous liquid be a salt water. The salt can be any suitable salt,such as at least one of NaBr, CaCl₂, CaBr₂, ZnBr₂, KCl, NaCl, amagnesium salt, a bromide salt, a formate salt, an acetate salt, and anitrate salt. The crosslinkable ampholyte polymer and crosslinker caneffectively provide increased viscosity in aqueous solutions havingvarious total dissolved solids levels, or having various ppm saltconcentrations. The crosslinkable ampholyte polymer and crosslinker canprovide effective increased viscosity of a salt water having anysuitable total dissolved solids level (e.g., wherein the dissolvedsolids correspond to dissolved salts), such as about 1,000 mg/L to about250,000 mg/L, or about 1,000 mg/L or less, or about 5,000 mg/L, 10,000,15,000, 20,000, 25,000, 30,000, 40,000, 50,000, 75,000, 100,000,125,000, 150,000, 175,000, 200,000, 225,000, or about 250,000 mg/L ormore. The crosslinkable ampholyte polymer and crosslinker can provideeffective increased viscosity of a salt water having any suitable saltconcentration, such as about 1,000 ppm to about 300,000 ppm, or about1,000 ppm to about 150,000 ppm, or about 1,000 ppm or less, or about5,000 ppm, 10,000, 15,000, 20,000, 25,000, 30,000, 40,000, 50,000,75,000, 100,000, 125,000, 150,000, 175,000, 200,000, 225,000, 250,000,275,000, or about 300,000 ppm or more. In some examples, the aqueousliquid can have a concentration of at least one of NaBr, CaCl₂, CaBr₂,ZnBr₂, KCl, and NaCl of about 0.1% w/v to about 20% w/v, or about 0.1%w/v or less, or about 0.5% w/v, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, orabout 30% w/v or more.

The crosslinkable ampholyte polymer and crosslinker, or a reactionproduct thereof, can be sufficient to provide effective increasedviscosity to an aqueous liquid at various high temperatures. Forexample, the crosslinkable ampholyte polymer and crosslinker, or areaction product thereof, can provide effective increased viscosity atup to about 500° F., or up to about 490° F., 480, 470, 460, 450, 440,430, 420, 410, 400, 390, 380, 370, 360, 350, 340, 330, 320, 310, 300,290, 280, 270, 260, 250, 240, 230, 220, 210, 200, 190, 180, 170, 160,150, 140, 130, 120, 110, or up to about 100° F.

The method can include at least partially crosslinking the crosslinkableampholyte polymer to provide a crosslinked ampholyte polymer. Thecrosslinking can include at least partially reacting the crosslinkableampholyte polymer with at least the crosslinker to provide an at leastpartially crosslinked ampholyte polymer. The crosslinking can occur inany suitable location and at any suitable time. For example, thecrosslinking can occur above-surface, in the subterranean formation, ora combination thereof. In some embodiments, the crosslinking can betriggered by a suitable event, for example, chemical triggering (e.g.,contacting with one or more chemicals that initiate or catalyze thecrosslinking reaction), temperature triggering (e.g., raising thetemperature of the composition such that the crosslinking reactionoccurs), or a combination thereof.

Temperature triggering can include exposing the composition to suitablyhigh temperature in the subterranean formation wherein a higherviscosity is desired. Temperature-triggered crosslinking can includeexposing the composition to a temperature of about 100° F. to about 500°F., 125° F. to about 350° F., 125° F. to about 250° F., 175° F. to about250° F., or about 450° F. or more, or about 440° F., 430, 420, 410, 400,390, 380, 370, 360, 350, 340, 330, 320, 310, 300, 290, 280, 270, 260,250, 240, 230, 220, 210, 200, 190, 180, 170, 160, 150, 140, 130, 120,110, or about 100° F. or less.

The composition can have any suitable viscosity above surface and in thesubterranean formation, such that the composition can be used asdescribed herein. The viscosity can be affected by any suitablecomponent, such as one or more crosslinkable ampholyte polymers, one ormore crosslinkers, one or more crosslinked products of the crosslinkableampholyte polymer and the crosslinker, one or more secondaryviscosifiers, one or more secondary crosslinkers, one or morecrosslinked products of a secondary viscosifier and a secondarycrosslinker, or any combination thereof. In some embodiments, theviscosity is affected by one or more crosslinked products of thecrosslinkable ampholyte polymer. In some embodiments, the viscosity ofthe composition, at standard temperature and pressure and at a shearrate of about 50 s⁻¹ to about 500 s⁻¹, or about 50 s⁻¹ or less to about1000 s⁻¹ or more, is about 0.01 cP to about 10,000,000 cP, or about 0.01cP or less, or about 0.1 cP, 1, 2, 3, 4, 5, 10, 15, 20, 25, 50, 75, 100,150, 200, 250, 500, 750, 1,000, 1,250, 1,500, 2,000, 2,500, 5,000,10,000, 15,000, 20,000, 25,000, 50,000, 75,000, 100,000, 125,000,150,000, 175,000, 200,000, 225,000, 250,000, 500,000, 1,000,000,1,250,000, 1,500,000, 2,000,000, 2,500,000, 5,000,000, 7,500,000, orabout 10,000,000 cP or more. In some embodiments, the viscosity of thecomposition, at standard temperature and pressure and at a shear rate ofabout 0 s⁻¹ to about 1 s⁻¹, or about 0.1 s⁻¹ or less to about 1 s⁻¹ ormore, is about 0.01 cP to about 1,000,000 cP, or about 0.01 cP or less,or about 0.1 cP, 1, 2, 3, 4, 5, 10, 15, 20, 25, 50, 75, 100, 150, 200,250, 500, 750, 1,000, 1,250, 1,500, 2,000, 2,500, 5,000, 10,000, 15,000,20,000, 25,000, 50,000, 75,000, 100,000, 125,000, 150,000, 175,000,200,000, 225,000, 250,000, 500,000, 1,000,000, 1,250,000, 1,500,000,2,000,000, 2,500,000, 5,000,000, 7,500,000, or about 10,000,000 cP ormore.

Prior to the at least partial crosslinking of the composition, thecomposition can have any suitable viscosity. In some embodiments, theviscosity of the composition, at standard temperature and pressure andat a shear rate of about 50 s⁻¹ to about 500 s⁻¹, or about 50 s⁻¹ orless to about 1000 s⁻¹ or more, is about 0.01 cP to about 1,000,000 cP,about 0.01 cP to about 10,000 cP, or about 0.01 cP or less, or about 0.1cP, 1, 2, 3, 4, 5, 10, 15, 20, 25, 50, 75, 100, 150, 200, 250, 500, 750,1,000, 1,250, 1,500, 2,000, 2,500, 5,000, 10,000, 15,000, 20,000,25,000, 50,000, 75,000, 100,000, 125,000, 150,000, 175,000, 200,000,225,000, 250,000, 500,000, or about 1,000,000 cP or more.

After the at least partial crosslinking of the composition, thecomposition can have any suitable viscosity. In some embodiments, afterthe crosslinking, the viscosity of the composition, at standardtemperature and pressure and at a shear rate of about 50 s⁻¹ to about500 s⁻¹, or about 50 s⁻¹ or less to about 1000 s⁻¹ or more, can be about10 cP to about 10,000,000 cP (e.g., the composition can be a gel withessentially infinite viscosity), about 1,000 cP to about 500,000 cP, orabout 10 cP or less, or about 15 cP, 20, 25, 50, 75, 100, 150, 200, 250,500, 750, 1,000, 1,250, 1,500, 2,000, 2,500, 5,000, 10,000, 15,000,20,000, 25,000, 50,000, 75,000, 100,000, 125,000, 150,000, 175,000,200,000, 225,000, 250,000, 500,000, 1,000,000, 1,250,000, 1,500,000,2,000,000, 2,500,000, 5,000,000, 7,500,000, or about 10,000,000 cP ormore. In some embodiments, after the crosslinking, the viscosity of thecomposition, at standard temperature and pressure and at a shear rate ofabout 0 s⁻¹ to about 1 s⁻¹, or about 0.1 s⁻¹ or less to about 1 s⁻¹ ormore, can be about 10 cP to about 1,000,000 cP, about 1,000 cP to about500,000 cP, or about 10 cP or less, or about 15 cP, 20, 25, 50, 75, 100,150, 200, 250, 500, 750, 1,000, 1,250, 1,500, 2,000, 2,500, 5,000,10,000, 15,000, 20,000, 25,000, 50,000, 75,000, 100,000, 125,000,150,000, 175,000, 200,000, 225,000, 250,000, 500,000, 1,000,000,1,250,000, 1,500,000, 2,000,000, 2,500,000, 5,000,000, 7,500,000, orabout 10,000,000 cP or more.

After the at least partial crosslinking of the composition, thecomposition can have any suitable shear stress (e.g., the compositioncan be a gel with essentially infinite viscosity). In some embodiments,after the crosslinking, the shear stress of the composition can be about0.1 Pa to about 500,000 Pa, about 1 Pa to about 1,000 Pa, about 1 Pa toabout 500 Pa, about 0.1 Pa or less, about 0.5 Pa, 1, 2, 3, 4, 5, 10, 15,20, 25, 50, 75, 100, 150, 200, 250, 500, 750, 1,000, 1,250, 1,500,1,750, 2,000, 2,500, 5,000, 10,000, 20,000, 25,000, 50,000, 75,000,100,000, 250,000, 500,000, 750,000, or about 1,000,000 Pa or more.

In some embodiments, the crosslinkable ampholyte polymer is sufficientsuch that, when crosslinked in an aqueous solution at a concentration ofabout 40 gpt with a polyethyleneimine crosslinker at a concentration ofabout 10 ppt to form a crosslinked ampholyte polymer, at 77° F. andstandard pressure, with a strain of about 10%, at a frequency of about0.1 rad/s to about 100 rad/s, or about 0.1 rad/s or less to about 1000rad/s or more, the aqueous solution comprising the crosslinked ampholytepolymer has a loss modulus G″ of about 0.1 Pa to about 1000 Pa, about0.1 Pa to about 100 Pa, about 0.1 Pa to about 10 Pa, or about 0.1 Pa orless, or about 0.5 Pa, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40,50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550,600, 700, 800, 900, or about 1,000 Pa or more. In some embodiments, thecrosslinkable ampholyte polymer is sufficient such that, whencrosslinked in an aqueous solution at a concentration of about 40 gptwith a polyethyleneimine crosslinker at a concentration of about 10 pptto form a crosslinked ampholyte polymer, at 150° F. and standardpressure, with a strain of about 10%, at a frequency of about 0.1 rad/sto about 100 rad/s, or about 0.1 rad/s or less to about 1000 rad/s ormore, the aqueous solution comprising the crosslinked polymer has astorage modulus G′ of about 10 Pa to about 1000 Pa, or about 10 Pa toabout 100 Pa, or about 10 Pa or less, or about 20 Pa, 30, 40, 50, 60,70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 700,800, 900, or about 1,000 Pa or more. In some embodiments, thecrosslinkable ampholyte polymer is sufficient such that, whencrosslinked in an aqueous solution at a concentration of about 40 gptwith a polyethyleneimine crosslinker at a concentration of about 10 pptto form a crosslinked ampholyte polymer, at 150° F. and standardpressure, with a strain of about 10%, at a frequency of about 0.1 rad/sto about 100 rad/s, or about 0.1 rad/s or less to about 1000 rad/s ormore, the aqueous solution comprising the crosslinked polymer has a lossmodulus G″ of about 0.5 Pa to about 10 Pa, or about 0.5 to about 5 Pa,or about 0.5 Pa or less, or about 1 Pa, 2, 3, 4, 5, 6, 7, 8, 9, or about10 Pa or more.

Crosslinkable Ampholyte Polymer.

The composition includes at least one crosslinkable ampholyte polymer,or a crosslinked reaction product thereof (e.g., a reaction product of acrosslinking reaction between the crosslinkable ampholyte polymer and acrosslinker). The crosslinkable ampholyte polymer can include anethylene repeating unit including a —C(O)NH₂ group, an ethylenerepeating unit including an —S(O)₂OR¹ group, and an ethylene repeatingunit including an —N⁺R² ₃X⁻ group. At each occurrence, R¹ can beindependently selected from the group consisting of —H and a counterion.At each occurrence, R² can be independently substituted or unsubstituted(C₁-C₂₀)hydrocarbyl, and at each occurrence, X⁻ can be independently acounterion.

Any suitable concentration of the crosslinkable ampholyte polymer can bepresent in the composition, such that the composition can be used asdescribed herein. In some embodiments, about 0.001 wt % to about 95 wt %of the composition is the one or more crosslinkable ampholyte polymers,or about 30 wt % to about 95 wt %, or about 70 wt % to about 90 wt %, orabout 0.001 wt % or less, or about 0.01 wt %, 0.1, 1, 2, 3, 4, 5, 10,15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 86, 87, 88,89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.9, 99.99, or about 99.999wt % or more of the composition is the one or more crosslinkableampholyte polymers. In some examples, for a composition including thecrosslinkable ampholyte polymer and an aqueous component, about 0.001 wt% to about 50 wt % of the composition is the one or more crosslinkableampholyte polymers, or about 0.01 wt % to about 10 wt % of thecomposition, about 0.01 wt % to about 30 wt %, or about 0.001 wt % orless, or about 0.01 wt %, 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35,40, 45, or about 50 wt % or more of the composition is the one or morecrosslinkable ampholyte polymers. In some examples, for a compositionincluding the crosslinkable ampholyte polymer or a reaction productthereof and an aqueous component, about 0.001 vol % to about 30 vol % ofthe composition is the one or more crosslinkable ampholyte polymers or areaction product thereof, or is the combined volume of the crosslinkableampholyte polymers and the crosslinker, or about 0.001 vol % or less, orabout 0.01 vol %, 0.1, 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22,24, 26, 28, or about 30 vol % or more.

The crosslinkable ampholyte polymer can have about Z^(wt) wt % of theethylene repeating unit including the —C(O)NH₂ group, wherein Z^(wt) isany suitable wt %, such as about 10% to about 70%, about 30% to about50%, or about 10% or less, or about 15%, 20, 25, 30, 31, 32, 33, 34, 35,36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 55, 60, 65%,or about 70% or more. The crosslinkable ampholyte polymer can have aboutZ^(mol) mol % of the ethylene repeating unit including the —C(O)NH₂group, wherein Z^(mol) is any suitable mol %, such as about 5% to about50%, about 10% to about 25%, or about 5% or less, or about 10%, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, 40, 45, orabout 50% or more.

The crosslinkable ampholyte polymer can have about N^(wt) wt % of theethylene repeating unit including the —S(O)₂OR¹ group, wherein N^(wt) wt% is any suitable wt %, such as about 1% to about 40%, 5% to about 15%,or about 1% or less, or about 5%, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,20, 25, 30, 35, or about 40% or more. The crosslinkable ampholytepolymer can have about N^(mol) mol % of the ethylene repeating unitincluding the —S(O)₂OR¹ group, wherein N^(mol) mol % is any suitable mol%, such as about 1% to about 40%, 5% to about 20%, or about 1% or less,5%, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35,or about 40% or more.

The crosslinkable ampholyte polymer can have about M^(wt) wt % of theethylene repeating unit including the —N⁺R² ₃X⁻ group, wherein M^(wt) wt% is any suitable wt %, such as about 20% to about 80%, 40% to about60%, or about 20% or less, 25%, 30, 35, 40, 41, 42, 43, 44, 45, 46, 47,48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 65, 70, 75, or about80% or more. The crosslinkable ampholyte polymer can have about M^(mol)mol % of the ethylene repeating unit including the —N⁺R² ₃X⁻ group,wherein M^(mol) mol % is any suitable mol %, such as about 40% to about90%, 55% to about 70%, or about 40% or less, 45, 50, 55, 56, 57, 58, 59,60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 75, 80, 85, or about 90% ormore.

In various embodiments, the crosslinkable ampholyte polymer is aterpolymer, e.g., Z^(wt)+N^(wt)+M^(wt) is about 100%, andZ^(mol)+N^(mol)+M^(mol) is about 100%.

The crosslinkable ampholyte polymer can have any suitable molecularweight, such as about 100,000 g/mol to about 20,000,000 g/mol, 2,000,000g/mol to about 20,000,000 g/mol, about 5,000,000 g/mol to about15,000,000 g/mol, or about 100,000 g/mol or less, or about 200,000g/mol, 300,000, 400,000, 500,000, 750,000, 1,000,000, 2,000,000,3,000,000, 4,000,000, 6,000,000, 8,000,000, 10,000,000, 12,000,000,14,000,000, 16,000,000, 18,000,000, or about 20,000,000 g/mol or more.

In various embodiments, the crosslinkable ampholyte polymer includesrepeating units having the structure:

The repeating units are in a block, alternate, or random configuration,and each repeating unit is independently in the orientation shown or inthe opposite orientation.

At each occurrence, R¹ can be independently selected from the groupconsisting of —H and a counterion. At each occurrence R¹ can beindependently selected from the group consisting of —H, Na⁺, K⁺, Li⁺,NH₄ ⁺, Zn⁺, Ca²⁺, Zn²⁺, Al³⁺, and Mg²⁺. At each occurrence, R¹ can be—H.

At each occurrence, R² can be independently substituted or unsubstituted(C₁-C₂₀)hydrocarbyl. At each occurrence R² can be independently(C₁-C₂₀)alkyl. At each occurrence R² can be independently (C₁-C₁₀)alkyl.At each occurrence R² can be independently selected from the groupconsisting of methyl, ethyl, propyl, butyl, and pentyl. At eachoccurrence, R² can be methyl.

At each occurrence, X⁻ can independently be a counterion. For example,the counterion can be a halide, such as fluoro, chloro, iodo, or bromo.In other examples, the counterion can be nitrate, hydrogen sulfate,dihydrogen phosphate, bicarbonate, nitrite, perchlorate, iodate,chlorate, bromate, chlorite, hypochlorite, hypobromite, cyanide, amide,cyanate, hydroxide, permanganate. The counterion can be a conjugate baseof any carboxylic acid, such as acetate or formate. In some embodiments,a counterion can have a negative charge greater than −1, which can insome embodiments complex to multiple ionized groups, such as oxide,sulfide, nitride, arsenate, phosphate, arsenite, hydrogen phosphate,sulfate, thio sulfate, sulfite, carbonate, chromate, dichromate,peroxide, or oxalate. At each occurrence, X⁻ can be Cl⁻.

At each occurrence R³, R⁴, and R⁵ can each independently be selectedfrom the group consisting of —H and a substituted or unsubstituted C₁-C₅hydrocarbyl. At each occurrence R³, R⁴, and R⁵ can be independentlyselected from the group consisting of —H and a C₁-C₅ alkyl. At eachoccurrence R³, R⁴, and R⁵ can be independently selected from the groupconsisting of —H and a C₁-C₃ alkyl (e.g., methyl, ethyl, or propyl). Ateach occurrence R³, R⁴, and R⁵ can be each —H.

At each occurrence L¹, L², and L³ can be each independently selectedfrom the group consisting of a bond and a substituted or unsubstitutedC₁-C₂₀ hydrocarbyl interrupted or terminated with 0, 1, 2, or 3 of atleast one of —NR³—, —S—, and —O—.

At each occurrence L¹ can be independently selected from the groupconsisting of a bond and -(substituted or unsubstituted C₁-C₂₀hydrocarbyl)-NR³— (substituted or unsubstituted C₁-C₂₀ hydrocarbyl)-. Ateach occurrence L¹ can be independently —C(O)—NH-(substituted orunsubstituted C₁-C₁₉ hydrocarbyl)-. At each occurrence L¹ can beindependently —C(O)—NH—(C₁-C₅ hydrocarbyl)-. The variable L¹ can be—C(O)—NH—CH(CH₃)₂—CH₂—.

At each occurrence, L² can be independently selected from the groupconsisting of —O—(C₁-C₂₀)hydrocarbyl- and —NR³—(C₁-C₂₀)hydrocarbyl-. Ateach occurrence, L² can be independently selected from —O—(C₁-C₁₀)alkyl-and —NH—(C₁-C₁₀)alkyl-. At each occurrence, L² can be independentlyselected from —O—CH₂—CH₂— and —NH—CH₂—CH₂.

At each occurrence L³ can be independently selected from the groupconsisting of a bond and C₁-C₂₀ hydrocarbyl. At each occurrence L³ canbe independently selected from the group consisting of a bond and C₁-C₅alkyl. At each occurrence L³ can be a bond.

The variable n can be about 4 to about 40,000, about 90 to about 40,000,about 450 to about 14,500, or about 4 or less, or about 5, 6, 7, 8, 9,10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 200, 250, 500, 750,1,000, 1,250, 1,500, 1,750, 2,000, 2,250, 2,500, 3,000, 3,500, 4,000,4,500, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 11,000, 12,000,13,000, 14,000, 15,000, 20,000, 25,000, 30,000, 35,000, or about 40,000or more.

The variable m can be about 100 to about 83,000, about 2,000 to about83,000, about 4,000 to about 62,000, or about 100 or less, or about 200,300, 400, 500, 750, 1,000, 1,500, 2,000, 3,000, 4,000, 7,500, 10,000,15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000,60,000, 65,000, 70,000, 75,000, 80,000, or about 85,000 or more.

The variable z can be about 125 to about 200,000, about 2,500 to about200,000, about 8,500 to about 140,000, or about 125 or less, 150, 175,200, 250, 300, 400, 500, 750, 1,000, 1,500, 2,000, 2,500, 3,000, 4,000,5,000, 10,000, 15,000, 20,000, 25,000, 30,000, 40,000, 50,000, 60,000,70,000, 80,000, 90,000, 100,000, 110,000, 120,000, 130,000, 140,000,150,000, 160,000, 170,000, 180,000, 190,000, or about 200,000 or more.

In some embodiments, the crosslinkable ampholyte polymer can be derivedfrom acrylamide, acryloyloxyethyl trimethylammonium chloride, and2-acrylamido-2-methylpropane sulfonic acid (AMPS) or a salt thereof, andincludes repeating units having the structure:

The repeating units are in a block, alternate, or random configuration,and each repeating unit is independently in the orientation shown or inthe opposite orientation.

In some embodiments, the crosslinkable ampholyte polymer can be derivedfrom acrylamide, methacrylamidopropyl trimethylammonium chloride, and2-acrylamido-2-methylpropane sulfonic acid (AMPS) or a salt thereof, andincludes repeating units having the structure:

The repeating units are in a block, alternate, or random configuration,and each repeating unit is independently in the orientation shown or inthe opposite orientation.Crosslinker.

The composition including the crosslinkable ampholyte polymer caninclude one or more crosslinkers. The crosslinker can be any suitablecrosslinker, such that the composition can be used as described herein.

In some embodiments, the crosslinker can be at least one of apoly(amino(C₂-C₁₀)hydrocarbylene) crosslinker and a (C₆-C₂₀)arylalcohol-(C₁-C₂₀)aldehyde crosslinker. In some examples, the crosslinkercan be at least one of polyethyleneimine, phenol-formaldehyde, andglyoxal. In some embodiments, the crosslinker is polyethyleneimine.

In some embodiments, the crosslinker can be a molecule including atleast one of chromium, aluminum, antimony, zirconium, titanium, calcium,boron, iron, silicon, copper, zinc, magnesium, and an ion thereof. Thecrosslinker can be at least one of boric acid, borax, a borate, a(C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbyl ester of a(C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbylboronicacid-modified polyacrylamide, ferric chloride, disodium octaboratetetrahydrate, sodium metaborate, sodium diborate, sodium tetraborate,disodium tetraborate, a pentaborate, ulexite, colemanite, magnesiumoxide, zirconium lactate, zirconium triethanol amine, zirconium lactatetriethanolamine, zirconium carbonate, zirconium acetylacetonate,zirconium malate, zirconium citrate, zirconium diisopropylamine lactate,zirconium glycolate, zirconium triethanol amine glycolate, zirconiumlactate glycolate, titanium lactate, titanium malate, titanium citrate,titanium ammonium lactate, titanium triethanolamine, titaniumacetylacetonate, aluminum lactate, and aluminum citrate.

In some embodiments, the crosslinker includes zirconium or a zirconiumderivative. The crosslinker can include at least one of zirconiumlactate, zirconium triethanol amine, zirconium lactate triethanolamine,zirconium carbonate, zirconium acetylacetonate, zirconium malate,zirconium citrate, zirconium diisopropylamine lactate, zirconiumglycolate, zirconium triethanol amine glycolate, and zirconium lactateglycolate.

The composition can include any suitable concentration of the one ormore crosslinkers. For example, 0.000,1 wt % to about 80 wt % of thecomposition can be the one or more crosslinkers, or about 0.001 wt % toabout 80 wt %, 10 wt % to about 30 wt %, or about 0.000,1 wt % or less,or about 0.001 wt %, 0.01, 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35,40, 45, 50, 55, 60, 65, 70, 75, or about 80 wt % or more of thecomposition can be the one or more crosslinkers. In some examples, inembodiments of the composition including an aqueous composition, about0.000,1 wt % to about 50 wt % of the composition is the crosslinker, orabout 0.001 wt % to about 1 wt %, or about 0.000,1 wt % or less, orabout 0.001 wt %, 0.01, 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40,45, or about 50 wt % or more of the composition.

Other Components.

In various embodiments, the composition including the crosslinkableampholyte polymer and the crosslinker can further include one or moresuitable additional components. The additional components can be anysuitable additional components, such that the composition can be used asdescribed herein.

The composition can further include one or more fluids. The compositioncan include a fluid including at least one of water, an organic solvent,and an oil. The composition can include a fluid including at least oneof dipropylene glycol methyl ether, dipropylene glycol dimethyl ether,dimethyl formamide, diethylene glycol methyl ether, ethylene glycolbutyl ether, diethylene glycol butyl ether, propylene carbonate,D-limonene, a C₂-C₄₀ fatty acid C₁-C₁₀ alkyl ester, 2-butoxy ethanol,butyl acetate, furfuryl acetate, dimethyl sulfoxide, dimethyl formamide,diesel, kerosene, mineral oil, a hydrocarbon including an internalolefin, a hydrocarbon including an alpha olefin, xylenes, an ionicliquid, methyl ethyl ketone, and cyclohexanone. The composition canfurther include at least one of water, brine, produced water, flowbackwater, brackish water, and sea water. The composition can include anysuitable proportion of the one or more fluids, such as about 0.001 wt %to 99.999 wt %, about 0.01 wt % to about 99.99 wt %, about 0.1 wt % toabout 99.9 wt %, or about 20 wt % to about 90 wt %, or about 0.001 wt %or less, or about 0.01 wt %, 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50,60, 70, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.9, 99.99, orabout 99.999 wt % or more of the composition.

The composition can further include a secondary viscosifier, in additionto the crosslinkable ampholyte polymer. The secondary viscosifier can bepresent in any suitable concentration, such as more, less, or an equalconcentration as compared to the concentration of the crosslinkableampholyte polymer. The secondary viscosifier can include at least one ofa substituted or unsubstituted polysaccharide, and a substituted orunsubstituted polyalkenylene, wherein the polysaccharide orpolyalkenylene is crosslinked or uncrosslinked. The secondaryviscosifier can include a polymer including at least one monomerselected from the group consisting of ethylene glycol, acrylamide, vinylacetate, 2-acrylamidomethylpropane sulfonic acid or its salts,trimethylammoniumethyl acrylate halide, and trimethylammoniumethylmethacrylate halide. The secondary viscosifier can include a crosslinkedgel or a crosslinkable gel.

The secondary viscosifier can affect the viscosity of the composition atany suitable time and location. In some embodiments, the secondaryviscosifier provides an increased viscosity at least one of beforeplacement in the subterranean formation, at the time of placement intothe subterranean formation, during travel in the subterranean formation,once the composition reaches a particular location in the subterraneanformation, or some period of time after the composition reaches aparticular location in the subterranean formation. In some embodiments,the secondary viscosifier can provide some or no increased viscosityuntil the secondary viscosifier reaches a desired location, at whichpoint the secondary viscosifier can provide a small or large increase inviscosity.

In some embodiments, the secondary viscosifier includes at least one ofa linear polysaccharide, and poly((C₂-C₁₀)alkenylene), wherein at eachoccurrence, the (C₂-C₁₀)alkenylene is independently substituted orunsubstituted. In some embodiments, the secondary viscosifier caninclude at least one of poly(acrylic acid) or (C₁-C₅)alkyl estersthereof, poly(methacrylic acid) or (C₁-C₅)alkyl esters thereof,poly(vinyl acetate), poly(vinyl alcohol), poly(ethylene glycol),poly(vinyl pyrrolidone), polyacrylamide, poly (hydroxyethylmethacrylate), alginate, chitosan, curdlan, dextran, emulsan, gellan,glucuronan, N-acetyl-glucosamine, N-acetyl-heparosan, hyaluronic acid,kefiran, lentinan, levan, mauran, pullulan, scleroglucan, schizophyllan,stewartan, succinoglycan, xanthan, welan, derivatized starch, tamarind,tragacanth, guar gum, derivatized guar (e.g., hydroxypropyl guar,carboxy methyl guar, or carboxymethyl hydroxylpropyl guar), gum ghatti,gum arabic, locust bean gum, and derivatized cellulose (e.g.,carboxymethyl cellulose, hydroxyethyl cellulose, carboxymethylhydroxyethyl cellulose, hydroxypropyl cellulose, or methyl hydroxylethyl cellulose).

In some embodiments, the secondary viscosifier can include a poly(vinylalcohol) homopolymer, poly(vinyl alcohol) copolymer, a crosslinkedpoly(vinyl alcohol) homopolymer, and a crosslinked poly(vinyl alcohol)copolymer. The secondary viscosifier can include a poly(vinyl alcohol)copolymer or a crosslinked poly(vinyl alcohol) copolymer including atleast one of a graft, linear, branched, block, and random copolymer ofvinyl alcohol and at least one of a substituted or unsubstituted(C₂-C₅₀)hydrocarbyl having at least one aliphatic unsaturated C—C bondtherein, and a substituted or unsubstituted (C₂-C₅₀)alkene. Thesecondary viscosifier can include a poly(vinyl alcohol) copolymer or acrosslinked poly(vinyl alcohol) copolymer including at least one of agraft, linear, branched, block, and random copolymer of vinyl alcoholand at least one of vinyl phosphonic acid, vinylidene diphosphonic acid,substituted or unsubstituted 2-acrylamido-2-methylpropanesulfonic acid,a substituted or unsubstituted (C₁-C₂₀)alkenoic acid, propenoic acid,butenoic acid, pentenoic acid, hexenoic acid, octenoic acid, nonenoicacid, decenoic acid, acrylic acid, methacrylic acid, hydroxypropylacrylic acid, acrylamide, fumaric acid, methacrylic acid, hydroxypropylacrylic acid, vinyl phosphonic acid, vinylidene diphosphonic acid,itaconic acid, crotonic acid, mesoconic acid, citraconic acid, styrenesulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, vinylsulfonic acid, and a substituted or unsubstituted (C₁-C₂₀)alkyl esterthereof. The secondary viscosifier can include a poly(vinyl alcohol)copolymer or a crosslinked poly(vinyl alcohol) copolymer including atleast one of a graft, linear, branched, block, and random copolymer ofvinyl alcohol and at least one of vinyl acetate, vinyl propanoate, vinylbutanoate, vinyl pentanoate, vinyl hexanoate, vinyl 2-methyl butanoate,vinyl 3-ethylpentanoate, and vinyl 3-ethylhexanoate, maleic anhydride, asubstituted or unsubstituted (C₁-C₂₀)alkenoic substituted orunsubstituted (C₁-C₂₀)alkanoic anhydride, a substituted or unsubstituted(C₁-C₂₀)alkenoic substituted or unsubstituted (C₁-C₂₀)alkenoicanhydride, propenoic acid anhydride, butenoic acid anhydride, pentenoicacid anhydride, hexenoic acid anhydride, octenoic acid anhydride,nonenoic acid anhydride, decenoic acid anhydride, acrylic acidanhydride, fumaric acid anhydride, methacrylic acid anhydride,hydroxypropyl acrylic acid anhydride, vinyl phosphonic acid anhydride,vinylidene diphosphonic acid anhydride, itaconic acid anhydride,crotonic acid anhydride, mesoconic acid anhydride, citraconic acidanhydride, styrene sulfonic acid anhydride, allyl sulfonic acidanhydride, methallyl sulfonic acid anhydride, vinyl sulfonic acidanhydride, and an N—(C₁-C₁₀)alkenyl nitrogen containing substituted orunsubstituted (C₁-C₁₀)heterocycle. The secondary viscosifier can includea poly(vinyl alcohol) copolymer or a crosslinked poly(vinyl alcohol)copolymer including at least one of a graft, linear, branched, block,and random copolymer that includes a poly(vinylalcohol)-poly(acrylamide)copolymer, apoly(vinylalcohol)-poly(2-acrylamido-2-methylpropanesulfonic acid)copolymer, or a poly(vinylalcohol)-poly(N-vinylpyrrolidone) copolymer.The secondary viscosifier can include a crosslinked poly(vinyl alcohol)homopolymer or copolymer including a crosslinker including at least oneof chromium, aluminum, antimony, zirconium, titanium, calcium, boron,iron, silicon, copper, zinc, magnesium, and an ion thereof. Thesecondary viscosifier can include a crosslinked poly(vinyl alcohol)homopolymer or copolymer including a crosslinker including at least oneof an aldehyde, an aldehyde-forming compound, a carboxylic acid or anester thereof, a sulfonic acid or an ester thereof, a phosphonic acid oran ester thereof, an acid anhydride, and an epihalohydrin.

In some embodiments, the secondary viscosifier can be a polymerincluding at least one of, or the ampholyte polymer can include amonomer derived from at least one of, 2,2′-azobis(2,4-dimethylvaleronitrile), 2,2′-azobis(2,4-dimethyl-4-methoxy valeronitrile),acrylamide ethyltrimethyl ammonium chloride, acrylamide, acrylamido- andmethacrylamido-alkyl trialkyl ammonium salts, acrylamidomethylpropanesulfonic acid, acrylamidopropyl trimethyl ammonium chloride, acrylicacid, dimethylaminoethyl methacrylamide, dimethylaminoethylmethacrylate, dimethylaminopropyl methacrylamide,dimethylaminopropylmethacrylamide, dimethyldiallylammonium chloride,dimethylethyl acrylate, fumaramide, methacrylamide, methacrylamidopropyltrimethyl ammonium chloride,methacrylamidopropyldimethyl-n-dodecylammonium chloride,methacrylamidopropyldimethyl-n-octylammonium chloride,methacrylamidopropyltrimethylammonium chloride, methacryloylalkyltrialkyl ammonium salts, methacryloylethyl trimethyl ammonium chloride,methacrylylamidopropyldimethylcetylammonium chloride,N-(3-sulfopropyl)-N-methacrylamidopropyl-N,N-dimethyl ammonium betaine,N,N-dimethylacrylamide, N-methylacrylamide,nonylphenoxypoly(ethyleneoxy)ethylmethacrylate, partially hydrolyzedpolyacrylamide, poly 2-amino-2-methyl propane sulfonic acid, polyvinylalcohol, sodium 2-acrylamido-2-methylpropane sulfonate, quaternizeddimethylaminoethylacrylate, quaternized dimethylaminoethylmethacrylate,2-(methacryloyloxy)ethyltrimethylammonium methyl sulfate or sulfonicacid or a salt thereof, 2-(methacryloyloxy)ethyltrimethylammoniumchloride copolymer, or any combination thereof. In certain embodiments,the secondary viscosifier may include a derivatized cellulose thatincludes cellulose grafted with an allyl or a vinyl monomer, such asthose disclosed in U.S. Pat. Nos. 4,982,793, 5,067,565, and 5,122,549,the entire disclosures of which are incorporated herein by reference.

The composition can include any suitable proportion of the secondaryviscosifier, such as about 0.001 wt % to 99.999 wt %, about 0.01 wt % toabout 99.99 wt %, about 0.1 wt % to about 50 wt %, or about 0.1 wt % toabout 20 wt %, or about 0.001 wt % or less, or about 0.01 wt %, 0.1, 1,2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94,95, 96, 97, 98, 99, 99.9, 99.99, or about 99.999 wt % or more of thecomposition.

The composition can further include a secondary crosslinker. Thecrosslinker can be any suitable crosslinker. The secondary crosslinkercan be present in any suitable concentration, such as more, less, or anequal concentration as compared to the concentration of the crosslinker.In various embodiments, the secondary crosslinker can include at leastone of chromium, aluminum, antimony, zirconium, titanium, calcium,boron, iron, silicon, copper, zinc, magnesium, and an ion thereof. Thesecondary crosslinker can include at least one of boric acid, borax, aborate, a (C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbyl esterof a (C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbylboronicacid-modified polyacrylamide, ferric chloride, disodium octaboratetetrahydrate, sodium metaborate, sodium diborate, sodium tetraborate,disodium tetraborate, a pentaborate, ulexite, colemanite, magnesiumoxide, zirconium lactate, zirconium triethanol amine, zirconium lactatetriethanolamine, zirconium carbonate, zirconium acetylacetonate,zirconium malate, zirconium citrate, zirconium diisopropylamine lactate,zirconium glycolate, zirconium triethanol amine glycolate, zirconiumlactate glycolate, titanium lactate, titanium malate, titanium citrate,titanium ammonium lactate, titanium triethanolamine, titaniumacetylacetonate, aluminum lactate, and aluminum citrate. The compositioncan include any suitable proportion of the secondary crosslinker, suchas about 0.000,1 wt % to 99.999,9 wt %, about 0.01 wt % to about 99.99wt %, about 0.1 wt % to about 50 wt %, or about 0.1 wt % to about 20 wt%, or about 0.000,1 wt % or less, or about 0.001 wt %, 0.01, 0.1, 1, 2,3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94, 95,96, 97, 98, 99, 99.9, 99.99, 99.999, or about 99.999,9 wt % or more ofthe composition.

Some embodiments of the method can include breaking the compositionincluding the crosslinkable ampholyte polymers, especiallynon-crosslinked ampholyte polymer, but in some embodiments crosslinkedampholyte polymer can be broken. In some instances, breaking can beachieved by partially hydrolyzing the ampholyte polymers. Partialhydrolysis (or breaking) can be achieved by increasing the temperature,increasing the pH, or both.

In some instances, breaking can be achieved by exposure to the elevatedtemperatures in the wellbore and/or subterranean formation. For example,the bottom hole circulating temperature can be about 100° F. or greater(e.g., about 100° F. to about 200° F., about 120° F. to about 200° F.,or about 150° F. to about 200° F.). The rate of breaking (or partialhydrolysis and contraction of the ampholyte polymer) can depend on thecomposition of the ampholyte polymer, the relative ratios of themonomers of the ampholyte polymer, the TDS of the composition, and thelike. Therefore, in some instances, the method can include breaking thecomposition including the ampholyte polymer with minimal to no chemicalbreaker (e.g., less than about 1% of a chemical breaker).

In some instances, breaking can involve increasing the pH of thecomposition including the ampholyte polymeric compounds. Increasing thepH can be achieved by introducing a suitable breaking fluid or includinga suitable breaker in the composition (e.g., sodium perborate).

The composition described herein can, in some instances, be foamed. Asused herein the term “foam” refers to a two-phase composition having acontinuous liquid phase and a discontinuous gas phase. In someembodiments, the composition described herein can include a base fluid,a gas, a foaming agent, and an ampholyte polymeric compound.

Suitable gases can include, but are not limited to, nitrogen, carbondioxide, air, methane, helium, argon, and any combination thereof. Oneskilled in the art, with the benefit of this disclosure, shouldunderstand the benefit of each gas. By way of nonlimiting example,carbon dioxide foams can have deeper well capability than nitrogen foamsbecause carbon dioxide emulsions have greater density than nitrogen gasfoams so that the surface pumping pressure required to reach acorresponding depth is lower with carbon dioxide than with nitrogen.Moreover, the higher density can impart greater proppant transportcapability, up to about 12 lb of proppant per gal of composition.

In some embodiments, the quality of a foamed composition can range froma lower limit of about 5%, 10%, 25%, 40%, 50%, 60%, or 70% gas volume toan upper limit of about 95%, 90%, 80%, 75%, 60%, or 50% gas volume, andwherein the quality of the foamed composition can range from any lowerlimit to any upper limit and encompasses any subset therebetween. Thefoamed composition can have a foam quality from about 85% to about 95%,or about 90% to about 95%.

Suitable foaming agents can include, but are not limited to, cationicfoaming agents, anionic foaming agents, amphoteric foaming agents,nonionic foaming agents, or any combination thereof. Nonlimitingexamples of suitable foaming agents can include, but are not limited to,surfactants like betaines, sulfated or sulfonated alkoxylates, alkylquarternary amines, alkoxylated linear alcohols, alkyl sulfonates, alkylaryl sulfonates, C₁₀-C₂₀ alkyldiphenyl ether sulfonates, polyethyleneglycols, ethers of alkylated phenol, sodium dodecylsulfate, alpha olefinsulfonates such as sodium dodecane sulfonate, trimethyl hexadecylammonium bromide, and the like, any derivative thereof, or anycombination thereof. Foaming agents can be included in compositions atconcentrations ranging typically from about 0.05% to about 2% of theliquid component by weight (e.g., from about 0.5 to about 20 gallons per1000 gallons of liquid).

The composition including the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, can be combinedwith any suitable downhole fluid before, during, or after the placementof the composition in the subterranean formation or the contacting ofthe composition and the subterranean material. In some examples, thecomposition including the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, is combined witha downhole fluid above the surface, and then the combined composition isplaced in a subterranean formation or contacted with a subterraneanmaterial. In another example, the composition including thecrosslinkable ampholyte polymer and the crosslinker, or a crosslinkedreaction product thereof, is injected into a subterranean formation tocombine with a downhole fluid, and the combined composition is contactedwith a subterranean material or is considered to be placed in thesubterranean formation. In various examples, at least one of prior to,during, and after the placement of the composition in the subterraneanformation or contacting of the subterranean material and thecomposition, the composition is used in the subterranean formation, atleast one of alone and in combination with other materials, as adrilling fluid, stimulation fluid, fracturing fluid, spotting fluid,clean-up fluid, completion fluid, remedial treatment fluid, abandonmentfluid, pill, acidizing fluid, cementing fluid, packer fluid, or acombination thereof.

In various embodiments, the method includes combining the compositionincluding the crosslinkable ampholyte polymer and the crosslinker, or acrosslinked reaction product thereof, with any suitable downhole fluid,such as an aqueous or oil-based fluid including a drilling fluid,stimulation fluid, fracturing fluid, spotting fluid, clean-up fluid,completion fluid, remedial treatment fluid, abandonment fluid, pill,acidizing fluid, cementing fluid, packer fluid, or a combinationthereof, to form a mixture. The placement of the composition in thesubterranean formation can include contacting the subterranean materialand the mixture. The contacting of the subterranean material and thecomposition can include contacting the subterranean material and themixture. Any suitable weight percent of a mixture that is placed in thesubterranean formation or contacted with the subterranean material canbe the composition including the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, such as about0.001 wt % to 99.999 wt %, about 0.01 wt % to about 99.99 wt %, about0.1 wt % to about 99.9 wt %, or about 20 wt % to about 90 wt %, or about0.001 wt % or less, or about 0.01 wt %, 0.1, 1, 2, 3, 4, 5, 10, 15, 20,30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99,99.9, 99.99 wt %, or about 99.999 wt % or more of the mixture orcomposition.

In some embodiments, the composition can include any suitable amount ofany suitable material used in a downhole fluid. For example, thecomposition can include water, saline, aqueous base, acid, oil, organicsolvent, synthetic fluid oil phase, aqueous solution, alcohol or polyol,cellulose, starch, alkalinity control agents, acidity control agents,density control agents, density modifiers, emulsifiers, dispersants,polymeric stabilizers, crosslinking agents, polyacrylamide, a polymer orcombination of polymers, antioxidants, heat stabilizers, foam controlagents, foaming agents, solvents, diluents, plasticizer, filler orinorganic particle, pigment, dye, precipitating agent, rheologymodifier, oil-wetting agents, set retarding additives, surfactants,gases, weight reducing additives, heavy-weight additives, lostcirculation materials, filtration control additives, salts, fibers,thixotropic additives, breakers, crosslinkers, rheology modifiers,curing accelerators, curing retarders, pH modifiers, chelating agents,scale inhibitors, enzymes, resins, water control materials, oxidizers,markers, Portland cement, pozzolana cement, gypsum cement, high aluminacontent cement, slag cement, silica cement, fly ash, metakaolin, shale,zeolite, a crystalline silica compound, amorphous silica, hydratableclays, microspheres, pozzolan lime, or a combination thereof. In variousembodiments, the composition can include one or more additive componentssuch as: thinner additives such as COLDTROL®, ATC®, OMC 2™, and OMC 42™;RHEMOD™, a viscosifier and suspension agent including a modified fattyacid; additives for providing temporary increased viscosity, such as forshipping (e.g., transport to the well site) and for use in sweeps (forexample, additives having the trade name TEMPERUS™ (a modified fattyacid) and VIS-PLUS®, a thixotropic viscosifying polymer blend);TAU-MOD™, a viscosifying/suspension agent including an amorphous/fibrousmaterial; additives for filtration control, for example, ADAPTA®, a HTHPfiltration control agent including a crosslinked copolymer; DURATONE®HT, a filtration control agent that includes an organophilic lignite,more particularly organophilic leonardite; THERMO TONE™, a hightemperature high pressure (HTHP) filtration control agent including asynthetic polymer; BDF™-366, a HTHP filtration control agent; BDF™-454,a HTHP filtration control agent; LIQUITONE™, a polymeric filtrationagent and viscosifier; additives for HTHP emulsion stability, forexample, FACTANT™, which includes highly concentrated tall oilderivative; emulsifiers such as LE SUPERMUL™ and EZ MUL® NT,polyaminated fatty acid emulsifiers, and FORTI-MUL®; DRIL TREAT®, an oilwetting agent for heavy fluids; BARACARB®, a sized ground marblebridging agent; BAROID®, a ground barium sulfate weighting agent;BAROLIFT®, a hole sweeping agent; SWEEP-WATE®, a sweep weighting agent;BDF-508, a diamine dimer rheology modifier; GELTONE® II organophilicclay; BAROFIBRE™ O for lost circulation management and seepage lossprevention, including a natural cellulose fiber; STEELSEAL®, a resilientgraphitic carbon lost circulation material; HYDRO-PLUG®, a hydratableswelling lost circulation material; lime, which can provide alkalinityand can activate certain emulsifiers; and calcium chloride, which canprovide salinity. Any suitable proportion of the composition can includeany optional component listed in this paragraph, such as about 0.000,1wt % to 99.999,9 wt %, about 0.01 wt % to about 99.99 wt %, about 0.1 wt% to about 99.9 wt %, or about 20 wt % to about 90 wt %, or about0.000,1 wt % or less, or about 0.001 wt %, 0.01, 0.1, 1, 2, 3, 4, 5, 10,15, 20, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98,99, 99.9, 99.99, 99.999 wt %, or 99.999,9 wt % or more of thecomposition.

A drilling fluid, also known as a drilling mud or simply “mud,” is aspecially designed fluid that is circulated through a wellbore as thewellbore is being drilled to facilitate the drilling operation. Thedrilling fluid can be water-based or oil-based. The drilling fluid cancarry cuttings up from beneath and around the bit, transport them up theannulus, and allow their separation. Also, a drilling fluid can cool andlubricate the drill head as well as reduce friction between the drillstring and the sides of the hole. The drilling fluid aids in support ofthe drill pipe and drill head, and provides a hydrostatic head tomaintain the integrity of the wellbore walls and prevent well blowouts.Specific drilling fluid systems can be selected to optimize a drillingoperation in accordance with the characteristics of a particulargeological formation. The drilling fluid can be formulated to preventunwanted influxes of formation fluids from permeable rocks and also toform a thin, low permeability filter cake that temporarily seals pores,other openings, and formations penetrated by the bit. In water-baseddrilling fluids, solid particles are suspended in a water or brinesolution containing other components. Oils or other non-aqueous liquidscan be emulsified in the water or brine or at least partiallysolubilized (for less hydrophobic non-aqueous liquids), but water is thecontinuous phase. A drilling fluid can be present in the mixture withthe composition including the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, in any suitableamount, such as about 1 wt % or less, about 2 wt %, 3, 4, 5, 10, 15, 20,30, 40, 50, 60, 70, 80, 85, 90, 95, 96, 97, 98, 99, 99.9, 99.99, 99.999,or about 99.999,9 wt % or more of the mixture.

A water-based drilling fluid in embodiments of the present invention canbe any suitable water-based drilling fluid. In various embodiments, thedrilling fluid can include at least one of water (fresh or brine), asalt (e.g., calcium chloride, sodium chloride, potassium chloride,magnesium chloride, calcium bromide, sodium bromide, potassium bromide,calcium nitrate, sodium formate, potassium formate, cesium formate),aqueous base (e.g., sodium hydroxide or potassium hydroxide), alcohol orpolyol, cellulose, starches, alkalinity control agents, density controlagents such as a density modifier (e.g., barium sulfate), surfactants(e.g., betaines, alkali metal alkylene acetates, sultaines, ethercarboxylates), emulsifiers, dispersants, polymeric stabilizers,crosslinking agents, polyacrylamides, polymers or combinations ofpolymers, antioxidants, heat stabilizers, foam control agents, foamingagents, solvents, diluents, plasticizers, filler or inorganic particles(e.g., silica), pigments, dyes, precipitating agents (e.g., silicates oraluminum complexes), and rheology modifiers such as thickeners orviscosifiers (e.g., xanthan gum). Any ingredient listed in thisparagraph can be either present or not present in the mixture.

An oil-based drilling fluid or mud in embodiments of the presentinvention can be any suitable oil-based drilling fluid. In variousembodiments the drilling fluid can include at least one of an oil-basedfluid (or synthetic fluid), saline, aqueous solution, emulsifiers, otheragents of additives for suspension control, weight or density control,oil-wetting agents, fluid loss or filtration control agents, andrheology control agents. For example, see H. C. H. Darley and George R.Gray, Composition and Properties of Drilling and Completion Fluids66-67, 561-562 (5^(th) ed. 1988). An oil-based or invert emulsion-baseddrilling fluid can include between about 10:90 to about 95:5, or about50:50 to about 95:5, by volume of oil phase to water phase. Asubstantially all oil mud includes about 100% liquid phase oil by volume(e.g., substantially no internal aqueous phase).

A pill is a relatively small quantity (e.g., less than about 500 bbl, orless than about 200 bbl) of drilling fluid used to accomplish a specifictask that the regular drilling fluid cannot perform. For example, a pillcan be a high-viscosity pill to, for example, help lift cuttings out ofa vertical wellbore. In another example, a pill can be a freshwater pillto, for example, dissolve a salt formation. Another example is apipe-freeing pill to, for example, destroy filter cake and relievedifferential sticking forces. In another example, a pill is a lostcirculation material pill to, for example, plug a thief zone. A pill caninclude any component described herein as a component of a drillingfluid.

A cement fluid can include an aqueous mixture of at least one of cementand cement kiln dust. The composition including the crosslinkableampholyte polymer and the crosslinker, or a crosslinked reaction productthereof, can form a useful combination with cement or cement kiln dust.The cement kiln dust can be any suitable cement kiln dust. Cement kilndust can be formed during the manufacture of cement and can be partiallycalcined kiln feed that is removed from the gas stream and collected ina dust collector during a manufacturing process. Cement kiln dust can beadvantageously utilized in a cost-effective manner since kiln dust isoften regarded as a low value waste product of the cement industry. Someembodiments of the cement fluid can include cement kiln dust but nocement, cement kiln dust and cement, or cement but no cement kiln dust.The cement can be any suitable cement. The cement can be a hydrauliccement. A variety of cements can be utilized in accordance withembodiments of the present invention; for example, those includingcalcium, aluminum, silicon, oxygen, iron, or sulfur, which can set andharden by reaction with water. Suitable cements can include Portlandcements, pozzolana cements, gypsum cements, high alumina contentcements, slag cements, silica cements, and combinations thereof. In someembodiments, the Portland cements that are suitable for use inembodiments of the present invention are classified as Classes A, C, H,and G cements according to the American Petroleum Institute, APISpecification for Materials and Testing for Well Cements, APISpecification 10, Fifth Ed., Jul. 1, 1990. A cement can be generallyincluded in the cementing fluid in an amount sufficient to provide thedesired compressive strength, density, or cost. In some embodiments, thehydraulic cement can be present in the cementing fluid in an amount inthe range of from 0 wt % to about 100 wt %, 0-95 wt %, 20-95 wt %, orabout 50-90 wt %. A cement kiln dust can be present in an amount of atleast about 0.01 wt %, or about 5 wt %-80 wt %, or about 10 wt % toabout 50 wt %.

Optionally, other additives can be added to a cement or kilndust-containing composition of embodiments of the present invention asdeemed appropriate by one skilled in the art, with the benefit of thisdisclosure. Any optional ingredient listed in this paragraph can beeither present or not present in the composition. For example, thecomposition can include fly ash, metakaolin, shale, zeolite, setretarding additive, surfactant, a gas, accelerators, weight reducingadditives, heavy-weight additives, lost circulation materials,filtration control additives, dispersants, and combinations thereof. Insome examples, additives can include crystalline silica compounds,amorphous silica, salts, fibers, hydratable clays, microspheres,pozzolan lime, thixotropic additives, combinations thereof, and thelike.

In various embodiments, the composition or mixture can include aproppant, a resin-coated proppant, an encapsulated resin, or acombination thereof. A proppant is a material that keeps an inducedhydraulic fracture at least partially open during or after a fracturingtreatment. Proppants can be transported into the subterranean formationand to the fracture using fluid, such as fracturing fluid or anotherfluid. A higher-viscosity fluid can more effectively transport proppantsto a desired location in a fracture, especially larger proppants, bymore effectively keeping proppants in a suspended state within thefluid. Examples of proppants can include sand, gravel, glass beads,polymer beads, ground products from shells and seeds such as walnuthulls, and manmade materials such as ceramic proppant, bauxite,tetrafluoroethylene materials (e.g., TEFLON™ available from DuPont),fruit pit materials, processed wood, composite particulates preparedfrom a binder and fine grade particulates such as silica, alumina, fumedsilica, carbon black, graphite, mica, titanium dioxide, meta-silicate,calcium silicate, kaolin, talc, zirconia, boron, fly ash, hollow glassmicrospheres, and solid glass, or mixtures thereof. In some embodiments,proppant can have an average particle size, wherein particle size is thelargest dimension of a particle, of about 0.001 mm to about 3 mm, about0.15 mm to about 2.5 mm, about 0.25 mm to about 0.43 mm, about 0.43 mmto about 0.85 mm, about 0.85 mm to about 1.18 mm, about 1.18 mm to about1.70 mm, or about 1.70 to about 2.36 mm. In some embodiments, theproppant can have a distribution of particle sizes clustering aroundmultiple averages, such as one, two, three, or four different averageparticle sizes. The composition or mixture can include any suitableamount of proppant, such as about 0.000,1 wt % to about 99.9 wt %, about0.1 wt % to about 80 wt %, or about 10 wt % to about 60 wt %, or about0.000,000,01 wt % or less, or about 0.000,001 wt %, 0.000,1, 0.001,0.01, 0.1, 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 85, 90,91, 92, 93, 94, 95, 96, 97, 98, 99, 99.9 wt %, or about 99.99 wt % ormore.

Drilling Assembly.

Embodiments of the composition including the crosslinkable ampholytepolymer and the crosslinker, or a crosslinked reaction product thereof,disclosed herein may directly or indirectly affect one or morecomponents or pieces of equipment associated with the preparation,delivery, recapture, recycling, reuse, and/or disposal of thecomposition including crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof. For example, andwith reference to FIG. 1, an embodiment of the composition including thecrosslinkable ampholyte polymer and the crosslinker, or a crosslinkedreaction product thereof, and optionally also including a drillingfluid, may directly or indirectly affect one or more components orpieces of equipment associated with an exemplary wellbore drillingassembly 100, according to one or more embodiments. It should be notedthat while FIG. 1 generally depicts a land-based drilling assembly,those skilled in the art will readily recognize that the principlesdescribed herein are equally applicable to subsea drilling operationsthat employ floating or sea-based platforms and rigs, without departingfrom the scope of the disclosure.

As illustrated, the drilling assembly 100 may include a drillingplatform 102 that supports a derrick 104 having a traveling block 106for raising and lowering a drill string 108. The drill string 108 mayinclude, but is not limited to, drill pipe and coiled tubing, asgenerally known to those skilled in the art. A kelly 110 supports thedrill string 108 as it is lowered through a rotary table 112. A drillbit 114 is attached to the distal end of the drill string 108 and isdriven either by a downhole motor and/or via rotation of the drillstring 108 from the well surface. As the bit 114 rotates, it creates awellbore 116 that penetrates various subterranean formations 118.

A pump 120 (e.g., a mud pump) circulates drilling fluid 122 through afeed pipe 124 and to the kelly 110, which conveys the drilling fluid 122downhole through the interior of the drill string 108 and through one ormore orifices in the drill bit 114. The drilling fluid 122 is thencirculated back to the surface via an annulus 126 defined between thedrill string 108 and the walls of the wellbore 116. At the surface, therecirculated or spent drilling fluid 122 exits the annulus 126 and maybe conveyed to one or more fluid processing unit(s) 128 via aninterconnecting flow line 130. After passing through the fluidprocessing unit(s) 128, a “cleaned” drilling fluid 122 is deposited intoa nearby retention pit 132 (e.g., a mud pit). While illustrated as beingarranged at the outlet of the wellbore 116 via the annulus 126, thoseskilled in the art will readily appreciate that the fluid processingunit(s) 128 may be arranged at any other location in the drillingassembly 100 to facilitate its proper function, without departing fromthe scope of the disclosure.

The composition including the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, may be added tothe drilling fluid 122 via a mixing hopper 134 communicably coupled toor otherwise in fluid communication with the retention pit 132. Themixing hopper 134 may include, but is not limited to, mixers and relatedmixing equipment known to those skilled in the art. In otherembodiments, however, the composition including the crosslinkableampholyte polymer and the crosslinker, or a crosslinked reaction productthereof, may be added to the drilling fluid 122 at any other location inthe drilling assembly 100. In at least one embodiment, for example,there could be more than one retention pit 132, such as multipleretention pits 132 in series. Moreover, the retention pit 132 may berepresentative of one or more fluid storage facilities and/or unitswhere the composition including the crosslinkable ampholyte polymer andthe crosslinker, or a crosslinked reaction product thereof, may bestored, reconditioned, and/or regulated until added to the drillingfluid 122.

As mentioned above, the composition including the crosslinkableampholyte polymer and the crosslinker, or a crosslinked reaction productthereof, may directly or indirectly affect the components and equipmentof the drilling assembly 100. For example, the composition including thecrosslinkable ampholyte polymer and the crosslinker, or a crosslinkedreaction product thereof, may directly or indirectly affect the fluidprocessing unit(s) 128, which may include, but is not limited to, one ormore of a shaker (e.g., shale shaker), a centrifuge, a hydrocyclone, aseparator (including magnetic and electrical separators), a desilter, adesander, a separator, a filter (e.g., diatomaceous earth filters), aheat exchanger, or any fluid reclamation equipment. The fluid processingunit(s) 128 may further include one or more sensors, gauges, pumps,compressors, and the like used to store, monitor, regulate, and/orrecondition the composition including the crosslinkable ampholytepolymer and the crosslinker, or a crosslinked reaction product thereof.

The composition including the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, may directly orindirectly affect the pump 120, which representatively includes anyconduits, pipelines, trucks, tubulars, and/or pipes used to fluidicallyconvey the composition including the crosslinkable ampholyte polymer andthe crosslinker, or a crosslinked reaction product thereof, downhole,any pumps, compressors, or motors (e.g., topside or downhole) used todrive the composition into motion, any valves or related joints used toregulate the pressure or flow rate of the composition, and any sensors(e.g., pressure, temperature, flow rate, and the like), gauges, and/orcombinations thereof, and the like. The composition including thecrosslinkable ampholyte polymer and the crosslinker, or a crosslinkedreaction product thereof, may also directly or indirectly affect themixing hopper 134 and the retention pit 132 and their assortedvariations.

The composition including the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, may alsodirectly or indirectly affect the various downhole equipment and toolsthat may come into contact with the composition including thecrosslinkable ampholyte polymer and the crosslinker, or a crosslinkedreaction product thereof, such as, but not limited to, the drill string108, any floats, drill collars, mud motors, downhole motors, and/orpumps associated with the drill string 108, and any measurement whiledrilling (MWD)/logging while drilling (LWD) tools and related telemetryequipment, sensors, or distributed sensors associated with the drillstring 108. The composition including the crosslinkable ampholytepolymer and the crosslinker, or a crosslinked reaction product thereof,may also directly or indirectly affect any downhole heat exchangers,valves and corresponding actuation devices, tool seals, packers andother wellbore isolation devices or components, and the like associatedwith the wellbore 116. The composition including the crosslinkableampholyte polymer and the crosslinker, or a crosslinked reaction productthereof, may also directly or indirectly affect the drill bit 114, whichmay include, but is not limited to, roller cone bits, polycrystallinediamond compact (PDC) bits, natural diamond bits, any hole openers,reamers, coring bits, and the like.

While not specifically illustrated herein, the composition including thecrosslinkable ampholyte polymer and the crosslinker, or a crosslinkedreaction product thereof, may also directly or indirectly affect anytransport or delivery equipment used to convey the composition includingthe crosslinkable ampholyte polymer and the crosslinker, or acrosslinked reaction product thereof, to the drilling assembly 100 suchas, for example, any transport vessels, conduits, pipelines, trucks,tubulars, and/or pipes used to fluidically move the compositionincluding the crosslinkable ampholyte polymer and the crosslinker, or acrosslinked reaction product thereof, from one location to another, anypumps, compressors, or motors used to drive the composition into motion,any valves or related joints used to regulate the pressure or flow rateof the composition, and any sensors (e.g., pressure and temperature),gauges, and/or combinations thereof, and the like.

System or Apparatus.

In various embodiments, the present invention provides a system. Thesystem can be any suitable system that can include the use of anembodiment of the composition including the crosslinkable ampholytepolymer and the crosslinker described herein, or a crosslinked reactionproduct thereof, in a subterranean formation, or that can includeperformance of an embodiment of a method of using the compositiondescribed herein. The system can include a composition including anembodiment of the crosslinkable ampholyte polymer and the crosslinker,or including a reaction product thereof. The system can also include asubterranean formation including the composition therein. In someembodiments, the composition in the system can also include a downholefluid, such as at least one of an aqueous fracturing fluid and anaqueous drilling fluid.

In some embodiments, the system can include a drillstring disposed in awellbore, the drillstring including a drill bit at a downhole end of thedrillstring. The system can include an annulus between the drillstringand the wellbore. The system can also include a pump configured tocirculate the composition through the drill string, through the drillbit, and back above-surface through the annulus. The system can includea fluid processing unit configured to process the composition exitingthe annulus to generate a cleaned drilling fluid for recirculationthrough the wellbore. In some embodiments, the system can include atubular disposed in a wellbore, and a pump configured to pump thecomposition into the subterranean formation.

In various embodiments, the present invention provides an apparatus. Theapparatus can be any suitable apparatus that can use an embodiment ofthe composition described herein or that can be used to perform anembodiment of a method described herein.

Various embodiments provide systems and apparatus configured fordelivering the composition described herein to a subterranean locationand for using the composition therein, such as for drilling or hydraulicfracturing. In various embodiments, the system can include a pumpfluidly coupled to a tubular (e.g., any suitable type of oilfield pipe,such as pipeline, drill pipe, production tubing, and the like), thetubular containing a composition including the crosslinkable ampholytepolymer and the crosslinker, or a crosslinked reaction product thereof,described herein.

The pump can be a high pressure pump in some embodiments. As usedherein, the term “high pressure pump” will refer to a pump that iscapable of delivering a fluid downhole at a pressure of about 1000 psior greater. A high pressure pump can be used when it is desired tointroduce the composition to a subterranean formation at or above afracture gradient of the subterranean formation, but it can also be usedin cases where fracturing is not desired. In some embodiments, the highpressure pump can be capable of fluidly conveying particulate matter,such as proppant particulates, into the subterranean formation. Suitablehigh pressure pumps will be known to one having ordinary skill in theart and can include, but are not limited to, floating piston pumps andpositive displacement pumps.

In other embodiments, the pump can be a low pressure pump. As usedherein, the term “low pressure pump” will refer to a pump that operatesat a pressure of about 1000 psi or less. In some embodiments, a lowpressure pump can be fluidly coupled to a high pressure pump that isfluidly coupled to the tubular. That is, in such embodiments, the lowpressure pump can be configured to convey the composition to the highpressure pump. In such embodiments, the low pressure pump can “step up”the pressure of the composition before it reaches the high pressurepump.

In some embodiments, the systems or apparatuses described herein canfurther include a mixing tank that is upstream of the pump and in whichthe composition is formulated. In various embodiments, the pump (e.g., alow pressure pump, a high pressure pump, or a combination thereof) canconvey the composition from the mixing tank or other source of thecomposition to the tubular. In other embodiments, however, thecomposition can be formulated offsite and transported to a worksite, inwhich case the composition can be introduced to the tubular via the pumpdirectly from its shipping container (e.g., a truck, a railcar, a barge,or the like) or from a transport pipeline. In either case, thecomposition can be drawn into the pump, elevated to an appropriatepressure, and then introduced into the tubular for delivery downhole.

FIG. 2 shows an illustrative schematic of systems and apparatuses thatcan deliver embodiments of the compositions of the present invention toa subterranean location, according to one or more embodiments. It shouldbe noted that while FIG. 2 generally depicts a land-based system orapparatus, it is to be recognized that like systems and apparatuses canbe operated in subsea locations as well. Embodiments of the presentinvention can have a different scale than that depicted in FIG. 2. Asdepicted in FIG. 2, system or apparatus 1 can include mixing tank 10, inwhich an embodiment of the composition can be formulated. Thecomposition can be conveyed via line 12 to wellhead 14, where thecomposition enters tubular 16, with tubular 16 extending from wellhead14 into subterranean formation 18. Upon being ejected from tubular 16,the composition can subsequently penetrate into subterranean formation18. Pump 20 can be configured to raise the pressure of the compositionto a desired degree before its introduction into tubular 16. It is to berecognized that system or apparatus 1 is merely exemplary in nature andvarious additional components can be present that have not necessarilybeen depicted in FIG. 2 in the interest of clarity. Non-limitingadditional components that can be present include, but are not limitedto, supply hoppers, valves, condensers, adapters, joints, gauges,sensors, compressors, pressure controllers, pressure sensors, flow ratecontrollers, flow rate sensors, temperature sensors, and the like.

Although not depicted in FIG. 2, at least part of the composition can,in some embodiments, flow back to wellhead 14 and exit subterraneanformation 18. In some embodiments, the composition that has flowed backto wellhead 14 can subsequently be recovered, and in some examplesreformulated, and recirculated to subterranean formation 18.

It is also to be recognized that the disclosed composition can alsodirectly or indirectly affect the various downhole equipment and toolsthat can come into contact with the composition during operation. Suchequipment and tools can include, but are not limited to, wellborecasing, wellbore liner, completion string, insert strings, drill string,coiled tubing, slickline, wireline, drill pipe, drill collars, mudmotors, downhole motors and/or pumps, surface-mounted motors and/orpumps, centralizers, turbolizers, scratchers, floats (e.g., shoes,collars, valves, and the like), logging tools and related telemetryequipment, actuators (e.g., electromechanical devices, hydromechanicaldevices, and the like), sliding sleeves, production sleeves, plugs,screens, filters, flow control devices (e.g., inflow control devices,autonomous inflow control devices, outflow control devices, and thelike), couplings (e.g., electro-hydraulic wet connect, dry connect,inductive coupler, and the like), control lines (e.g., electrical, fiberoptic, hydraulic, and the like), surveillance lines, drill bits andreamers, sensors or distributed sensors, downhole heat exchangers,valves and corresponding actuation devices, tool seals, packers, cementplugs, bridge plugs, and other wellbore isolation devices or components,and the like. Any of these components can be included in the systems andapparatuses generally described above and depicted in FIG. 2.

Composition for Treatment of a Subterranean Formation.

Various embodiments provide a composition for treatment of asubterranean formation. The composition can be any suitable compositionincluding an embodiment of the crosslinkable ampholyte polymer and thecrosslinker, or a crosslinked reaction product thereof, that can be usedto perform an embodiment of the method for treatment of a subterraneanformation described herein. Various embodiments provide a crosslinkedreaction product of an embodiment of the composition herein, wherein atleast some of the crosslinkable ampholyte polymer has reacted with atleast some of the crosslinker to form a crosslinked product.

For example, the composition can include a crosslinkable ampholytepolymer having about Z^(wt) wt % of an ethylene repeating unit includingthe —C(O)NH₂ group, about N^(wt) wt % of an ethylene repeating unitincluding a —S(O)₂OR¹ group, and about M^(wt) wt % of an ethylenerepeating unit including an —N⁺R² ₃X⁻ group. At each occurrence R¹ canbe independently selected from the group consisting of —H and acounterion. At each occurrence, R² can be independently substituted orunsubstituted (C₁-C₂₀)hydrocarbyl. At each occurrence, X⁻ can beindependently a counterion. The repeating units are in block, alternate,or random configuration. The variable Z^(wt) can be about 10% to about70%, N^(wt) can be about 1% to about 40%, and M^(wt) can be about 20% toabout 80%. The crosslinkable ampholyte polymer can have a molecularweight of about 100,000 g/mol to about 20,000,000 g/mol. The compositioncan include at least one crosslinker. The composition can also include adownhole fluid. Additionally or alternatively to the compositionincluding the crosslinkable ampholyte polymer and the crosslinker, thecomposition can include a reaction product of the crosslinkableampholyte polymer and the crosslinker (e.g., a reaction product of acrosslinking reaction between the crosslinkable ampholyte polymer andthe crosslinker).

In some embodiments, the crosslinkable ampholyte polymer includesrepeating units having the structure:

At each occurrence R¹ can be independently selected from the groupconsisting of —H and a counterion. The repeating units are in a block,alternate, or random configuration, and each repeating unit isindependently in the orientation shown or in the opposite orientation.The crosslinkable ampholyte polymer can have a molecular weight of about100,000 g/mol to about 20,000,000 g/mol. The crosslinkable ampholytepolymer can have about 30 wt % to about 50 wt % of the ethylenerepeating unit including the —C(O)NH₂ group, about 5 wt % to about 15 wt% of the ethylene repeating unit including the —S(O)₂OR¹ group, andabout 40 wt % to about 60 wt % of the ethylene repeating unit includingthe —N⁺R² ₃X⁻ group. The composition can include a crosslinker includingpolyethyleneimine. The composition can also include a downhole fluidincluding at least one of a drilling fluid, a fracturing fluid, adiverting fluid, and a lost circulation treatment fluid. About 0.001 wt% to about 30 v/v % of the composition is the crosslinkable ampholytepolymer and the crosslinker, with the remainder being the downhole fluidand other optional components. Additionally or alternatively to thecomposition including the crosslinkable ampholyte polymer and thecrosslinker, the composition can include a reaction product of thecrosslinkable ampholyte polymer and the crosslinker (e.g., a reactionproduct of a crosslinking reaction between the crosslinkable ampholytepolymer and the crosslinker).Method for Preparing a Composition for Treatment of a SubterraneanFormation.

In various embodiments, the present invention provides a method forpreparing a composition for treatment of a subterranean formation. Themethod can be any suitable method that produces an embodiment of thecomposition including the crosslinkable ampholyte polymer and thecrosslinker, or a reaction product thereof, described herein. Forexample, the method can include forming a composition including anembodiment of the crosslinkable ampholyte polymer and the crosslinker,or a reaction product thereof. In some embodiments, the compositionfurther includes a downhole fluid.

EXAMPLES

Various embodiments of the present invention can be better understood byreference to the following Examples which are offered by way ofillustration. The present invention is not limited to the Examples givenherein.

Part I. Viscosifier Example 1

Two samples of an ampholyte polymeric compound including a terpolymer ofacrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyloxyethyl trimethyl ammonium chloride in water were prepared at 5 gal/1,000gal and 20 gal/1,000 gal. The ampholyte terpolymer had 40 wt % monomersfrom acrylamide, 10 wt % monomers from 2-acrylamido-2-methylpropanesulfonic acid, and 50 wt % monomers from acryloyloxy ethyl trimethylammonium chloride (AETAC). The samples were heated from 77° F. to 150°F. at a rate of 10° F./min and then held at a constant temperature of150° F. at a shear rate of 40 s⁻¹. As shown in FIG. 3, the viscosity atthe higher concentration reduces from about 155 cP to less than about 5cP in about 90 minutes, while at the lower concentration from about 35cP to less than about 5 cP in about 20-25 minutes.

This example illustrates that treatment fluids including the ampholytepolymeric compounds described herein can reduce in viscosity over time(e.g., can break over time), which can advantageously allow for the useof little to no breaker in the treatment fluids or in subsequentwellbore operations.

Example 2

Samples were prepared with (1) linear xanthan (known to viscosify highTDS fluids) at 60 lb/1,000 gal and (2) an ampholyte polymeric compoundincluding a terpolymer of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and acryloyloxy ethyl trimethyl ammonium chloride at 60gal/1,000 gal, each in base fluids of (1) water and (2) salt water withan additional 3% KCl. The ampholyte terpolymer had the same wt %distribution of monomers as the ampholyte terpolymer used in Example 1.The viscosity of each sample was analyzed at 77° F. and 150° F. at ashear rate of 40 s⁻¹. FIG. 4 (water samples) illustrates that theampholyte polymeric compound provides higher viscosity than linearxanthan in water. While FIG. 5 (salt water samples) illustrates that ina high TDS environment the ampholyte polymeric compound provides for acomparable viscosity to linear xanthan.

This example illustrates that treatment fluids can be viscosified tolevels comparable to that of traditional viscosifying agents, includingin high TDS fluids.

Part II. Friction Reduction Example 3

Samples were prepared with individual friction reducers at aconcentration of 1 gallon per thousand gallons (e.g., 0.1% by volume) inwater:

-   -   (1) a commercially available friction reducing agent containing        partially hydrolyzed polyacrylamide;    -   (2) a multi-component, cationic friction reducing agent; and    -   (3) an ampholyte polymeric compound including a terpolymer of        acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and        acryloyloxy ethyl trimethyl ammonium chloride. The ampholyte        terpolymer had the same wt % distribution of monomers as the        ampholyte terpolymer used in Example 1.

The salinity of the samples (measured as ppm of TDS) was then increasedas the percent friction reduction (“% FR”) was analyzed by pumping thesample through a test pipe while measuring the pressure drop with apressure transducer. The % FR was calculated based on the ratio betweenthe measured pressure drop of the sample and the pressure drop of afresh water control sample at the same tested flow rate and ambienttemperature and pressure.

As shown in FIG. 6, the Sample 1 showed an immediate decline in the % FRwith increased salinity and a dramatic drop in % FR to essentially nofriction reduction from about 100,000 to about 150,000 ppm TDS. Samples2 and 3 showed similar performance over the salinity range tested withonly about a 5%-10% variations in the % FR from 0 ppm to about 250,000ppm TDS.

This example demonstrates that the one-component friction reducing agentof an ampholyte polymeric compound outperforms other polymeric frictionreducing agents with increased TDS and provides comparable performanceto the more complex friction reducing agents, which tend to be expensiveand complicated to implement.

Example 4

Samples of an ampholyte polymeric compound including a terpolymer ofacrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyloxyethyl trimethyl ammonium chloride in water were analyzed for degradationrates by analyzing the viscosity of the fluid over time at varioustemperatures:

-   -   (1) room temperature;    -   (2) ramp to 150° F.; and    -   (3) ramp to 190° F.

The ampholyte terpolymer had the same wt % distribution of monomers asthe ampholyte terpolymer used in Example 1. As shown in FIG. 7, theviscosity of the room temperature sample decreased from about 4.75 cP toabout 1 cP over about 6 hours while the 150° F. sample decreased fromabout 5 cP to about 0.4 cP over about 25 minutes and the 190° F. sampledecreased from about 5 cP to about 0.4 cP over about 15 minutes.Reduction in viscosity to such levels indicates that the polymer waspartially hydrolyzed and contracted. As shown, the hydrolysis wastemperature dependent, indicating that in some instances the nativetemperature of the subterranean formation may be such that an ampholytepolymeric compound may be capable of breaking with minimal to noadditional breaker.

Example 5

Samples were prepared with (1) partially hydrolyzed polyacrylamide inwater (2) an ampholyte polymeric compound including a terpolymer ofacrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyloxyethyl trimethyl ammonium chloride in water. The ampholyte terpolymer hadthe same wt % distribution of monomers as the ampholyte terpolymer usedin Example 1. The concentration of each of the polymers was at infinitedilution. The intrinsic viscosity of the samples were measured overabout 75 hours. As illustrated in FIG. 8, the ampholyte polymericcompound sample reduced in intrinsic viscosity from about 95 dL/g toabout 2 dL/g, while the polyacrylamide sample had a relatively steadyintrinsic viscosity of about 100 dL/g over the 75 hour time frame. Thisdemonstrates that the ampholyte polymeric compounds may be capable ofbreaking over time without the use of chemical breakers due, at least inpart, to the partial hydrolysis of the ampholyte polymeric compound(e.g., the acryloyloxy ethyl trimethyl ammonium chloride to acrylicacid).

Example 6

Samples were prepared with an ampholyte polymeric compound including aterpolymer of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid,and acryloyloxy ethyl trimethyl ammonium chloride at 0.1 vol % in (1)water, (2) 50,000 ppm brine, and (3) 250,000 ppm brine. The ampholyteterpolymer had the same wt % distribution of monomers as the ampholyteterpolymer used in Example 1. The samples were heated to 150° F., andthe viscosity of each sample was analyzed at a shear rate of 40 s⁻¹.FIG. 9 illustrates that the sample in water achieved the highest initialviscosity, while both of the brine samples achieved about ⅓ the initialviscosity as the water sample. However, over time, the higher the TDS ofthe sample the less reduction in the viscosity (e.g., less hydrolysisand contraction of the ampholyte polymeric compound).

Example 7

Samples were prepared with (1) 0.1 vol % polyacrylamide, (2) 0.1 vol %polyacrylamide and 1 lb/1,000 gal of a chemical breaker, and (3) 0.1 vol% of an ampholyte polymeric compound including a terpolymer ofacrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyloxyethyl trimethyl ammonium chloride in water. The ampholyte terpolymer hadthe same wt % distribution of monomers as the ampholyte terpolymer usedin Example 1. Samples were run through various core/sand pack samples todetermine the regain permeability of the core/sand pack samples aftertreatment.

In the regain permeability tests, the initial permeability was measuredby flowing 7% KCl through the core/sand pack sample. Then, the sampleswere pumped through the core/sand pack sample at a rate of five porevolumes. The treated core/sand pack sample was shut-in overnight at 150°F. The permeability was once again tested by flowing 7% KCl through thecore/sand pack sample. Table 1 provides the initial permeability andpercent of permeability regained.

TABLE 1 Initial permeability and percent of permeability regained.Regain Fluid Sample Core/Sand Pack Initial Permeability Permeability (2)100 mesh sand pack  1.5 D 96% (3) 100 mesh sand pack  1.6 D 98% (1)Berea core  91 mD 29% (2) Berea core 106 mD 83% (3) Berea core  77 mD80% (2) Nugget  2.5 mD 54% (3) Nugget  1.8 mD 61%

This example demonstrates that the ampholyte polymeric compound, with noadditional chemical breaker, provides for similar or better regain inpermeability to a traditional friction reducer with a chemical breaker.

Part III. Crosslinked Polymer Example 8

An aqueous solution with 40 gpt ampholyte terpolymer and 10 gptpolyethyleneimine was prepared. The ampholyte terpolymer had the same wt% distribution of monomers as the ampholyte terpolymer used inExample 1. The terpolymer was crosslinked by exposing it to elevatedtemperature (150° F. for about 2 h). FIG. 10 shows a photo of thecrosslinked ampholyte terpolymer.

As a comparative sample, an aqueous solution of 25 ppt (parts perthousand) guar gum and 2 gpt crosslinker (an instant borate crosslinker)was crosslinked at room temperature.

Example 9 Viscosity Measurement

FIG. 11 shows the viscosity curve for the crosslinked ampholyteterpolymer of Example 8 at room temperature. It was a pseudoplasticfluid and exhibited a strong yield-stress. These properties can behelpful for fluid loss and diverting applications. The n and K valuewere 0.2 and 107.1 Pa*s^(0.2) respectively.

Example 10 Small Amplitude Oscillation Shear Testing

Small amplitude oscillation shear (SAOS) testing was performed tofurther investigate the structure of the crosslinked materials ofExample 8. FIG. 12 illustrates the results for the crosslinked ampholyteterpolymer and crosslinked guar gum at room temperature, with a strainof 10% for each test.

FIG. 12 shows that the storage modulus G′ of the crosslinked ampholyteterpolymer was relatively constant over a wide range of frequency and nocrossover was observed, indicating a solid-like material, and its G′ wasabout 10 times higher than the crosslinked guar.

FIG. 13 illustrates the SAOS test results for the crosslinked materialsat 150° F., again using 10% strain. At high temperatures, crosslinkedguar became a viscous fluid. As shown in FIG. 13, the G″ of thecrosslinked guar gum was greater than G′ over the tested frequency,illustrating that the proppant transport capability decreases due to thereduction in elasticity. In contrast, not much change was observed forthe crosslinked ampholyte terpolymer. Two conclusions can be drawn fromthis result. First, crosslinked ampholyte terpolymer had a much higherelasticity than crosslinked guar, which can help to suspend theproppant. Second, the crosslinked ampholyte polymer can tolerate highertemperatures than crosslinked guar, e.g., the gel has better temperaturestability.

Example 11 Core Flow Testing

Core flow testing was conducted to check the regain permeability forcrosslinked polyacrylamide and the crosslinked ampholyte terpolymer ofExample 8. The treatment fluid was flown through the core at 5 porevolume, and the cell was shut-in at 150° F. overnight. 7% KCl brine wasused to flow through the core and obtain the permeability data. FIG. 14illustrates the permeability profile for a crosslinked mixture of 40 gptpolyacrylamide (having 30 mol % hydrolyzed acrylamide units, having amolecular weight of about 10,000,000) with 10 gpt polyethyleneimine.FIG. 15 illustrates the permeability profile for a crosslinked mixtureof 40 gpt ampholyte terpolymer with 10 gpt PEI, where 5PV refers to 5pore volume, wherein the volume of the fluid is 5 times the pore volumeof the core. Table 2 summarizes the results for both tests.

TABLE 2 Summary of regain permeability for crosslinked polyacrylamideand crosslinked ampholyte terpolymer Regain Fluid Initial permeabilitypermeability 40 gpt polyacrylamide + 10 gpt 2.1 Darcy 1.21% PEI,crosslinked 40 gpt ampholyte terpolymer + 7.3 Darcy 0.01% 10 gpt PEI.crosslinked

Though the initial permeability for the crosslinked ampholyte terpolymertest was three times higher than the crosslinked polyacrylamide test, itstill showed almost 0% regain permeability after the treatment whereasthe crosslinked polyacrylamide showed 1.2% regain permeability. Thecrosslinked ampholyte terpolymer was more effective in reducing thepermeability of a formation.

The terms and expressions that have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible within the scope of theembodiments of the present invention. Thus, it should be understood thatalthough the present invention has been specifically disclosed byspecific embodiments and optional features, modification and variationof the concepts herein disclosed may be resorted to by those of ordinaryskill in the art, and that such modifications and variations areconsidered to be within the scope of embodiments of the presentinvention.

Additional Embodiments

The following exemplary embodiments are provided, the numbering of whichis not to be construed as designating levels of importance:

Embodiment 1 provides a method of treating a subterranean formation, themethod comprising:

obtaining or providing a composition comprising

-   -   a crosslinkable ampholyte polymer comprising an ethylene        repeating unit comprising a —C(O)NH₂ group, an ethylene        repeating unit comprising an —S(O)₂OR¹ group, and an ethylene        repeating unit comprising an —N⁺R² ₃X⁻ group, wherein        -   at each occurrence, R¹ is independently selected from the            group consisting of —H and a counterion,        -   at each occurrence, R² is independently substituted or            unsubstituted (C₁-C₂₀)hydrocarbyl, and        -   at each occurrence, X⁻ is independently a counterion; and    -   at least one crosslinker; and

placing the composition in a subterranean formation.

Embodiment 2 provides the method of Embodiment 1, wherein the obtainingor providing of the composition occurs above-surface.

Embodiment 3 provides the method of any one of Embodiments 1-2, whereinthe obtaining or providing of the composition occurs in the subterraneanformation.

Embodiment 4 provides the method of any one of Embodiments 1-3, whereinthe method is a method of drilling the subterranean formation.

Embodiment 5 provides the method of any one of Embodiments 1-4, whereinthe method is a method of fracturing the subterranean formation.

Embodiment 6 provides the method of any one of Embodiments 1-5, whereinthe method is a method of fluid loss control or diverting.

Embodiment 7 provides the method of any one of Embodiments 1-6, whereinthe composition comprises an aqueous liquid.

Embodiment 8 provides the method of Embodiment 7, wherein the methodfurther comprises mixing the aqueous liquid with the crosslinkableampholyte polymer and the crosslinker.

Embodiment 9 provides the method of Embodiment 8, wherein the mixingoccurs above surface.

Embodiment 10 provides the method of Embodiment 9, wherein the mixingoccurs in the subterranean formation.

Embodiment 11 provides the method of any one of Embodiments 7-10,wherein the aqueous liquid comprises at least one of water, brine,produced water, flowback water, brackish water, and sea water.

Embodiment 12 provides the method of any one of Embodiments 7-11,wherein the aqueous liquid comprises salt water having a total dissolvedsolids level of about 1,000 mg/L to about 300,000 mg/L.

Embodiment 13 provides the method of any one of Embodiments 7-12,wherein the aqueous liquid comprises at least one of a drilling fluid, afracturing fluid, a diverting fluid, and a lost circulation treatmentfluid.

Embodiment 14 provides the method of any one of Embodiments 1-13,further comprising at least partially crosslinking the crosslinkableampholyte polymer to provide a crosslinked ampholyte polymer.

Embodiment 15 provides the method of Embodiment 14, wherein thecrosslinking occurs at least partially above-surface.

Embodiment 16 provides the method of any one of Embodiments 14-15,wherein the crosslinking occurs at least partially in the subterraneanformation.

Embodiment 17 provides the method of any one of Embodiments 14-16,wherein the crosslinking is at least partially triggered by an increasein temperature.

Embodiment 18 provides the method of Embodiment 17, wherein the increasein temperature is at least partially due to placement of the compositionin the subterranean formation.

Embodiment 19 provides the method of any one of Embodiments 14-18,wherein the crosslinking comprises exposing the composition to atemperature of about 100° F. to about 450° F.

Embodiment 20 provides the method of any one of Embodiments 14-19,wherein the crosslinking comprises exposing the composition to atemperature of about 125° F. to about 250° F.

Embodiment 21 provides the method of any one of Embodiments 14-20,wherein after the crosslinking, a viscosity of the composition, atstandard temperature and pressure and at a shear rate of about 50 s⁻¹ toabout 500 s⁻¹, is about 10 cP to about 1,000,000 cP.

Embodiment 22 provides the method of any one of Embodiments 14-21,wherein after the crosslinking, a viscosity of the composition, atstandard temperature and pressure and at a shear rate of about 50 s⁻¹ toabout 500 s⁻¹, is about 1,000 cP to about 500,000 cP.

Embodiment 23 provides the method of any one of Embodiments 14-22,wherein after the crosslinking, a viscosity of the composition, atstandard temperature and pressure and at a shear rate of about 0 s⁻¹ toabout 1 s⁻¹, is about 10 cP to about 10,000,000 cP.

Embodiment 24 provides the method of any one of Embodiments 14-23,wherein after the crosslinking, a yield stress of the composition, atstandard temperature and pressure, is about 0.1 Pa and about 1,000 Pa.

Embodiment 25 provides the method of any one of Embodiments 14-24,wherein after the crosslinking, a yield stress of the composition, atstandard temperature and pressure, is about 1 Pa to about 500 Pa.

Embodiment 26 provides the method of any one of Embodiments 14-25,wherein prior to the crosslinking, a viscosity of the composition, atstandard temperature and pressure and at a shear rate of about 50 s⁻¹ toabout 500 s⁻¹, is about 0.01 cP to about 1,000,000 cP.

Embodiment 27 provides the method of any one of Embodiments 14-26,wherein prior to the crosslinking, a viscosity of the composition, atstandard temperature and pressure and at a shear rate of about 50 s⁻¹ toabout 500 s⁻¹, is about 0.01 cP to about 10,000 cP.

Embodiment 28 provides the method of any one of Embodiments 1-27,wherein the crosslinkable ampholyte polymer is sufficient such that,when crosslinked in an aqueous solution at a concentration of about 40gpt with a polyethyleneimine crosslinker at a concentration of about 10ppt to form a crosslinked ampholyte polymer, at 77° F. and standardpressure, with a strain of about 10%, at a frequency of about 0.1 rad/sto about 100 rad/s, the aqueous solution comprising the crosslinkedampholyte polymer has a loss modulus G″ of about 0.1 Pa to about 100 Pa.

Embodiment 29 provides the method of any one of Embodiments 1-28,wherein the crosslinkable ampholyte polymer is sufficient such that,when crosslinked in an aqueous solution at a concentration of about 40gpt with a polyethyleneimine crosslinker at a concentration of about 10ppt to form a crosslinked ampholyte polymer, at 150° F. and standardpressure, with a strain of about 10%, at a frequency of about 0.1 rad/sto about 100 rad/s, the aqueous solution comprising the crosslinkedpolymer has a storage modulus G′ of about 10 Pa to about 1000 Pa.

Embodiment 30 provides the method of any one of Embodiments 1-29,wherein the crosslinkable ampholyte polymer is sufficient such that,when crosslinked in an aqueous solution at a concentration of about 40gpt with a polyethyleneimine crosslinker at a concentration of about 10ppt to form a crosslinked ampholyte polymer, at 150° F. and standardpressure, with a strain of about 10%, at a frequency of about 0.1 rad/sto about 100 rad/s, the aqueous solution comprising the crosslinkedpolymer has a loss modulus G″ of about 0.5 Pa to about 10 Pa.

Embodiment 31 provides the method of any one of Embodiments 1-30,wherein about 0.001 wt % to about 95 wt % of the composition is thecrosslinkable ampholyte polymer.

Embodiment 32 provides the method of any one of Embodiments 1-31,wherein about 70 wt % to about 90 wt % of the composition is thecrosslinkable ampholyte polymer.

Embodiment 33 provides the method of any one of Embodiments 7-32,wherein about 0.01 wt % to about 50 wt % of the composition is thecrosslinkable ampholyte polymer.

Embodiment 34 provides the method of any one of Embodiments 7-33,wherein about 0.001 to about 30 v/v % of the composition is thecrosslinkable ampholyte polymer.

Embodiment 35 provides the method of any one of Embodiments 1-34,wherein the crosslinkable ampholyte polymer has about Z^(wt) wt % of theethylene repeating unit comprising the —C(O)NH₂ group, about N^(wt) wt %of the ethylene repeating unit comprising the —S(O)₂OR¹ group, and aboutM^(wt) wt % of the ethylene repeating unit comprising the —N⁺R² ₃X⁻group, wherein Z^(wt) is about 10% to about 70%, N^(wt) is about 1% toabout 40%, and M^(wt) is about 20% to about 80%.

Embodiment 36 provides the method of Embodiment 35, wherein Z^(wt) isabout 30% to about 50%, N^(wt) is about 5% to about 15%, and M^(wt) isabout 40% to about 60%.

Embodiment 37 provides the method of any one of Embodiments 35-36,wherein Z^(wt)+N^(wt)+M^(wt) is about 100%.

Embodiment 38 provides the method of any one of Embodiments 1-37,wherein the crosslinkable ampholyte polymer has about Z^(mol) mol % ofthe ethylene repeating unit comprising the —C(O)NH₂ group, about N^(mol)mol % of the ethylene repeating unit comprising the —S(O)₂OR¹ group, andabout M^(mol) mol % of the ethylene repeating unit comprising the —N⁺R²₃X⁻ group, wherein Z^(mol) is about 5% to about 50%, N^(mol) is about 1%to about 40%, and M^(mol) is about 40% to about 90%.

Embodiment 39 provides the method of Embodiment 38, wherein Z^(mol) isabout 10% to about 25%, N^(mol) is about 5% to about 20%, and M^(mol) isabout 55% to about 70%.

Embodiment 40 provides the method of any one of Embodiments 38-39,wherein Z^(mol)+N^(mol)+M^(mol) is about 100%.

Embodiment 41 provides the method of any one of Embodiments 1-40,wherein the crosslinkable ampholyte polymer has a molecular weight ofabout 100,000 g/mol to about 20,000,000 g/mol.

Embodiment 42 provides the method of any one of Embodiments 1-41,wherein the crosslinkable ampholyte polymer has a molecular weight ofabout 5,000,000 g/mol to about 15,000,000 g/mol.

Embodiment 43 provides the method of any one of Embodiments 1-42,wherein the crosslinkable ampholyte polymer comprises repeating unitshaving the structure:

wherein

-   -   at each occurrence R³, R⁴, and R⁵ are each independently        selected from the group consisting of —H and a substituted or        unsubstituted C₁-C₅ hydrocarbyl,    -   at each occurrence L¹, L², and L³ are each independently        selected from the group consisting of a bond and a substituted        or unsubstituted C₁-C₂₀ hydrocarbyl interrupted or terminated        with 0, 1, 2, or 3 of at least one of —NR³—, —S—, and —O—, and    -   the repeating units are in a block, alternate, or random        configuration, and each repeating unit is independently in the        orientation shown or in the opposite orientation.

Embodiment 44 provides the method of Embodiment 43, wherein at eachoccurrence L¹ is independently selected from the group consisting of abond and -(substituted or unsubstituted C₁-C₂₀ hydrocarbyl)-NR³—(substituted or unsubstituted C₁-C₂₀ hydrocarbyl)-.

Embodiment 45 provides the method of any one of Embodiments 43-44,wherein at each occurrence L¹ is independently —C(O)—NH-(substituted orunsubstituted C₁-C₁₉ hydrocarbyl)-.

Embodiment 46 provides the method of any one of Embodiments 43-45,wherein at each occurrence L¹ is independently —C(O)—NH—(C₁-C₅hydrocarbyl)-.

Embodiment 47 provides the method of any one of Embodiments 43-46,wherein L¹ is —C(O)—NH—CH(CH₃)₂—CH₂—.

Embodiment 48 provides the method of any one of Embodiments 43-47,wherein at each occurrence L² is independently selected from the groupconsisting of —O—(C₁-C₂₀)hydrocarbyl- and —NR³—(C₁-C₂₀)hydrocarbyl-.

Embodiment 49 provides the method of any one of Embodiments 43-48,wherein at each occurrence L² is independently selected from—O—(C₁-C₁₀)alkyl- and —NH—(C₁-C₁₀)alkyl-.

Embodiment 50 provides the method of any one of Embodiments 43-49,wherein at each occurrence L² is independently selected from —O—CH₂—CH₂—and —NH—CH₂—CH₂.

Embodiment 51 provides the method of any one of Embodiments 43-50,wherein at each occurrence L³ is independently selected from the groupconsisting of a bond and C₁-C₂₀ hydrocarbyl.

Embodiment 52 provides the method of any one of Embodiments 43-51,wherein at each occurrence L³ is independently selected from the groupconsisting of a bond and C₁-C₅ alkyl.

Embodiment 53 provides the method of any one of Embodiments 43-52,wherein at each occurrence L³ is a bond.

Embodiment 54 provides the method of any one of Embodiments 43-53,wherein at each occurrence R³, R⁴, and R⁵ are independently selectedfrom the group consisting of —H and a C₁-C₅ alkyl.

Embodiment 55 provides the method of any one of Embodiments 43-54,wherein at each occurrence R³, R⁴, and R⁵ are independently selectedfrom the group consisting of —H and a C₁-C₃ alkyl.

Embodiment 56 provides the method of any one of Embodiments 43-55,wherein at each occurrence R³, R⁴, and R⁵ are each —H.

Embodiment 57 provides the method of any one of Embodiments 43-56,wherein at each occurrence R¹ is independently selected from the groupconsisting of —H, Na⁺, K⁺, Li⁺, NH₄ ⁺, Zn⁺, Ca²⁺, Zn²⁺, Al³⁺, and Mg²⁺.

Embodiment 58 provides the method of any one of Embodiments 43-57,wherein at each occurrence R¹ is —H.

Embodiment 59 provides the method of any one of Embodiments 43-58,wherein at each occurrence R² is independently (C₁-C₂₀)alkyl.

Embodiment 60 provides the method of any one of Embodiments 43-59,wherein at each occurrence R² is independently (C₁-C₁₀)alkyl.

Embodiment 61 provides the method of any one of Embodiments 43-60,wherein at each occurrence R² is independently selected from the groupconsisting of methyl, ethyl, propyl, butyl, and pentyl.

Embodiment 62 provides the method of any one of Embodiments 43-61,wherein X⁻ is Cl⁻.

Embodiment 63 provides the method of any one of Embodiments 43-62,wherein n is about 4 to about 40,000.

Embodiment 64 provides the method of any one of Embodiments 43-63,wherein n is about 450 to about 14,500.

Embodiment 65 provides the method of any one of Embodiments 43-64,wherein m is about 100 to about 83,000.

Embodiment 66 provides the method of any one of Embodiments 43-65,wherein m is about 4,000 to about 62,000.

Embodiment 67 provides the method of any one of Embodiments 43-66,wherein z is about 125 to about 200,000.

Embodiment 68 provides the method of any one of Embodiments 43-67,wherein z is about 8,500 to about 140,000.

Embodiment 69 provides the method of any one of Embodiments 1-68,wherein the crosslinkable ampholyte polymer comprises repeating unitshaving the structure:

wherein the repeating units are in a block, alternate, or randomconfiguration, and each repeating unit is independently in theorientation shown or in the opposite orientation.

Embodiment 70 provides the method of any one of Embodiments 1-69,wherein the crosslinkable ampholyte polymer comprises repeating unitshaving the structure:

wherein the repeating units are in a block, alternate, or randomconfiguration, and each repeating unit is independently in theorientation shown or in the opposite orientation.

Embodiment 71 provides the method of any one of Embodiments 1-70,wherein about 0.000,1 wt % to about 80 wt % of the composition is thecrosslinker.

Embodiment 72 provides the method of any one of Embodiments 1-71,wherein about 1 wt % to about 30 wt % of the composition is thecrosslinker.

Embodiment 73 provides the method of any one of Embodiments 7-72,wherein about 0.000,1 wt % to about 50 wt % of the composition is thecrosslinker.

Embodiment 74 provides the method of any one of Embodiments 7-73,wherein about 0.001 wt % to about 5 wt % of the composition is thecrosslinker.

Embodiment 75 provides the method of any one of Embodiments 1-74,wherein the crosslinker comprises at least one of chromium, aluminum,antimony, zirconium, titanium, calcium, boron, iron, silicon, copper,zinc, magnesium, and an ion thereof.

Embodiment 76 provides the method of any one of Embodiments 1-75,wherein the crosslinker comprises at least one of apoly(amino(C₂-C₁₀)hydrocarbylene) crosslinker and a (C₆-C₂₀)arylalcohol-(C₁-C₂₀)aldehyde crosslinker.

Embodiment 77 provides the method of any one of Embodiments 1-76,wherein the crosslinker comprises at least one of polyethyleneimine,phenol-formaldehyde, and glyoxal.

Embodiment 78 provides the method of any one of Embodiments 1-77,wherein the crosslinker comprises at least one of boric acid, borax, aborate, a (C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbyl esterof a (C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbylboronicacid-modified polyacrylamide, ferric chloride, disodium octaboratetetrahydrate, sodium metaborate, sodium diborate, sodium tetraborate,disodium tetraborate, a pentaborate, ulexite, colemanite, magnesiumoxide, zirconium lactate, zirconium triethanol amine, zirconium lactatetriethanolamine, zirconium carbonate, zirconium acetylacetonate,zirconium malate, zirconium citrate, zirconium diisopropylamine lactate,zirconium glycolate, zirconium triethanol amine glycolate, zirconiumlactate glycolate, titanium lactate, titanium malate, titanium citrate,titanium ammonium lactate, titanium triethanolamine, titaniumacetylacetonate, aluminum lactate, and aluminum citrate.

Embodiment 79 provides the method of any one of Embodiments 1-78,wherein the composition further comprises a fluid comprising at leastone of water, an organic solvent, and an oil.

Embodiment 80 provides the method of any one of Embodiments 1-79,wherein the composition further comprises a fluid comprising at leastone of dipropylene glycol methyl ether, dipropylene glycol dimethylether, dimethyl formamide, diethylene glycol methyl ether, ethyleneglycol butyl ether, diethylene glycol butyl ether, propylene carbonate,D-limonene, a C₂-C₄₀ fatty acid C₁-C₁₀ alkyl ester, 2-butoxy ethanol,butyl acetate, furfuryl acetate, dimethyl sulfoxide, dimethyl formamide,diesel, kerosene, mineral oil, a hydrocarbon comprising an internalolefin, a hydrocarbon comprising an alpha olefin, xylenes, an ionicliquid, methyl ethyl ketone, and cyclohexanone.

Embodiment 81 provides the method of any one of Embodiments 1-80,wherein the composition further comprises a secondary viscosifier.

Embodiment 82 provides the method of Embodiment 81, wherein thesecondary viscosifier comprises at least one of a substituted orunsubstituted polysaccharide, and a substituted or unsubstitutedpolyalkenylene, wherein the polysaccharide or polyalkenylene iscrosslinked or uncrosslinked.

Embodiment 83 provides the method of any one of Embodiments 81-82,wherein the secondary viscosifier comprises a polymer comprising atleast one monomer selected from the group consisting of ethylene glycol,acrylamide, vinyl acetate, 2-acrylamidomethylpropane sulfonic acid orits salts, trimethylammoniumethyl acrylate halide, andtrimethylammoniumethyl methacrylate halide.

Embodiment 84 provides the method of any one of Embodiments 81-83,wherein the secondary viscosifier comprises a crosslinked gel or acrosslinkable gel.

Embodiment 85 provides the method of any one of Embodiments 81-84,wherein the secondary viscosifier comprises at least one of a linearpolysaccharide, and poly((C₂-C₁₀)alkenylene), wherein the(C₂-C₁₀)alkenylene is substituted or unsubstituted.

Embodiment 86 provides the method of any one of Embodiments 81-85,wherein the secondary viscosifier comprises at least one of poly(acrylicacid) or (C₁-C₅)alkyl esters thereof, poly(methacrylic acid) or(C₁-C₅)alkyl esters thereof, poly(vinyl acetate), poly(vinyl alcohol),poly(ethylene glycol), poly(vinyl pyrrolidone), polyacrylamide, poly(hydroxyethyl methacrylate), alginate, chitosan, curdlan, dextran,emulsan, a galactoglucopolysaccharide, gellan, glucuronan,N-acetyl-glucosamine, N-acetyl-heparosan, hyaluronic acid, kefiran,lentinan, levan, mauran, pullulan, scleroglucan, schizophyllan,stewartan, succinoglycan, xanthan, welan, derivatized starch, tamarind,tragacanth, guar gum, derivatized guar, gum ghatti, gum arabic, locustbean gum, derivatized cellulose, carboxymethyl cellulose, hydroxyethylcellulose, carboxymethyl hydroxyethyl cellulose, hydroxypropylcellulose, methyl hydroxyl ethyl cellulose, guar, hydroxypropyl guar,carboxy methyl guar, and carboxymethyl hydroxylpropyl guar.

Embodiment 87 provides the method of any one of Embodiments 81-86,wherein the secondary viscosifier comprises poly(vinyl alcohol)homopolymer, poly(vinyl alcohol) copolymer, a crosslinked poly(vinylalcohol) homopolymer, and a crosslinked poly(vinyl alcohol) copolymer.

Embodiment 88 provides the method of any one of Embodiments 1-87,wherein the composition further comprises a secondary crosslinkercomprising at least one of chromium, aluminum, antimony, zirconium,titanium, calcium, boron, iron, silicon, copper, zinc, magnesium, and anion thereof.

Embodiment 89 provides the method of Embodiment 88, wherein thesecondary crosslinker comprises at least one of boric acid, borax, aborate, a (C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbyl esterof a (C₁-C₃₀)hydrocarbylboronic acid, a (C₁-C₃₀)hydrocarbylboronicacid-modified polyacrylamide, ferric chloride, disodium octaboratetetrahydrate, sodium metaborate, sodium diborate, sodium tetraborate,disodium tetraborate, a pentaborate, ulexite, colemanite, magnesiumoxide, zirconium lactate, zirconium triethanol amine, zirconium lactatetriethanolamine, zirconium carbonate, zirconium acetylacetonate,zirconium malate, zirconium citrate, zirconium diisopropylamine lactate,zirconium glycolate, zirconium triethanol amine glycolate, zirconiumlactate glycolate, titanium lactate, titanium malate, titanium citrate,titanium ammonium lactate, titanium triethanolamine, titaniumacetylacetonate, aluminum lactate, and aluminum citrate.

Embodiment 90 provides the method of any one of Embodiments 1-89,further comprising combining the composition, or a crosslinked reactionproduct thereof, with an aqueous or oil-based fluid comprising adrilling fluid, stimulation fluid, fracturing fluid, spotting fluid,clean-up fluid, completion fluid, remedial treatment fluid, abandonmentfluid, pill, acidizing fluid, cementing fluid, packer fluid, or acombination thereof, to form a mixture, wherein the placing thecomposition in the subterranean formation comprises placing the mixturein the subterranean formation.

Embodiment 91 provides the method of any one of Embodiments 1-90,wherein at least one of prior to, during, and after the placing of thecomposition in the subterranean formation, the composition, or acrosslinked reaction product thereof, is used in the subterraneanformation, at least one of alone and in combination with othermaterials, as a drilling fluid, stimulation fluid, fracturing fluid,spotting fluid, clean-up fluid, completion fluid, remedial treatmentfluid, abandonment fluid, pill, acidizing fluid, cementing fluid, packerfluid, or a combination thereof.

Embodiment 92 provides the method of any one of Embodiments 1-91,wherein the composition further comprises water, saline, aqueous base,oil, organic solvent, synthetic fluid oil phase, aqueous solution,alcohol or polyol, cellulose, starch, alkalinity control agent, aciditycontrol agent, density control agent, density modifier, emulsifier,dispersant, polymeric stabilizer, crosslinking agent, polyacrylamide,polymer or combination of polymers, antioxidant, heat stabilizer, foamcontrol agent, foaming agent, solvent, diluent, plasticizer, filler orinorganic particle, pigment, dye, precipitating agent, rheologymodifier, oil-wetting agent, set retarding additive, surfactant,corrosion inhibitor, gas, weight reducing additive, heavy-weightadditive, lost circulation material, filtration control additive, salt,fiber, thixotropic additive, breaker, crosslinker, gas, rheologymodifier, curing accelerator, curing retarder, pH modifier, chelatingagent, scale inhibitor, enzyme, resin, water control material, polymer,oxidizer, a marker, Portland cement, pozzolana cement, gypsum cement,high alumina content cement, slag cement, silica cement, fly ash,metakaolin, shale, zeolite, a crystalline silica compound, amorphoussilica, fibers, a hydratable clay, microspheres, pozzolan lime, or acombination thereof.

Embodiment 93 provides the method of any one of Embodiments 1-92,wherein placing the composition in the subterranean formation comprisesfracturing at least part of the subterranean formation to form at leastone subterranean fracture.

Embodiment 94 provides the method of any one of Embodiments 1-93,wherein the composition further comprises a proppant, a resin-coatedproppant, or a combination thereof.

Embodiment 95 provides the method of any one of Embodiments 1-94,wherein the placing of the composition in the subterranean formation inthe subterranean formation comprises pumping the composition through adrill string disposed in a wellbore, through a drill bit at a downholeend of the drill string, and back above-surface through an annulus.

Embodiment 96 provides the method of Embodiment 95, further comprisingprocessing the composition exiting the annulus with at least one fluidprocessing unit to generate a cleaned composition and recirculating thecleaned composition through the wellbore.

Embodiment 97 provides a system configured to perform the method of anyone of Embodiments 1-96, the system comprising:

the composition comprising the crosslinkable ampholyte polymer and thecrosslinker; and

the subterranean formation comprising the composition therein.

Embodiment 98 provides the system of Embodiment 97, further comprising

a drillstring disposed in a wellbore, the drillstring comprising a drillbit at a downhole end of the drillstring;

an annulus between the drillstring and the wellbore; and

a pump configured to circulate the composition through the drill string,through the drill bit, and back above-surface through the annulus.

Embodiment 99 provides the system of Embodiment 98, further comprising afluid processing unit configured to process the composition exiting theannulus to generate a cleaned composition for recirculation through thewellbore.

Embodiment 100 provides a method of treating a subterranean formation,the method comprising:

obtaining or providing a composition comprising

-   -   a reaction product of a mixture comprising        -   a crosslinkable ampholyte polymer comprising an ethylene            repeating unit comprising a —C(O)NH₂ group, an ethylene            repeating unit comprising an —S(O)₂OR¹ group, and an            ethylene repeating unit comprising an —N⁺R² ₃X⁻ group,            wherein            -   at each occurrence, R¹ is independently selected from                the group consisting of —H and a counterion,            -   at each occurrence, R² is independently substituted or                unsubstituted (C₁-C₂₀)hydrocarbyl, and            -   at each occurrence, X⁻ is independently a counterion;                and        -   at least one crosslinker; and    -   placing the composition in a subterranean formation.

Embodiment 101 provides a method of treating a subterranean formation,the method comprising:

obtaining or providing a composition comprising

-   -   a crosslinkable ampholyte polymer comprising repeating units        having the structure:

-   -   wherein        -   at each occurrence, R¹ is independently selected from the            group consisting of —H and a counterion,        -   the repeating units are in a block, alternate, or random            configuration, and each repeating unit is independently in            the orientation shown or in the opposite orientation,        -   the crosslinkable ampholyte polymer has a molecular weight            of about 100,000 g/mol to about 20,000,000 g/mol, and        -   the crosslinkable ampholyte polymer has about 30 wt % to            about 50 wt % of the ethylene repeating unit comprising the            —C(O)NH₂ group, about 5 wt % to about 15 wt % of the            ethylene repeating unit comprising the —S(O)₂OR¹ group, and            about 40 wt % to about 60 wt % of the ethylene repeating            unit comprising the —N⁺R² ₃X⁻ group;    -   a crosslinker comprising polyethyleneimine; and    -   a downhole fluid comprising at least one of a drilling fluid, a        fracturing fluid, a diverting fluid, and a lost circulation        treatment fluid; and

placing the composition in a subterranean formation, wherein about 0.001wt % to about 30 v/v % of the composition is the crosslinkable ampholytepolymer and the crosslinker.

Embodiment 102 provides a system comprising:

a composition comprising

-   -   a crosslinkable ampholyte polymer having about Z^(wt) wt % of an        ethylene repeating unit comprising the —C(O)NH₂ group, about        N^(wt) wt % of an ethylene repeating unit comprising a —S(O)₂OR¹        group, and about M^(wt) wt % of an ethylene repeating unit        comprising an —N⁺R² ₃X⁻ group, wherein        -   at each occurrence R¹ is independently selected from the            group consisting of —H and a counterion,        -   at each occurrence, R² is independently substituted or            unsubstituted (C₁-C₂₀)hydrocarbyl,        -   at each occurrence, X⁻ is independently a counterion,        -   the repeating units are in block, alternate, or random            configuration,        -   Z^(wt) is about 10% to about 70%, N^(wt) is about 1% to            about 40%, and M^(wt) is about 20% to about 80%, and        -   the crosslinkable ampholyte polymer has a molecular weight            of about 100,000 g/mol to about 20,000,000 g/mol; and    -   at least one crosslinker; and

a subterranean formation comprising the composition therein.

Embodiment 103 provides the system of Embodiment 102, further comprising

a drillstring disposed in a wellbore, the drillstring comprising a drillbit at a downhole end of the drillstring;

an annulus between the drillstring and the wellbore; and

a pump configured to circulate the composition through the drill string,through the drill bit, and back above-surface through the annulus.

Embodiment 104 provides the system of Embodiment 103, further comprisinga fluid processing unit configured to process the composition exitingthe annulus to generate a cleaned drilling fluid for recirculationthrough the wellbore.

Embodiment 105 provides the system of any one of Embodiments 102-104,further comprising

a tubular disposed in the subterranean formation; and

a pump configured to pump the composition into the subterraneanformation through the tubular.

Embodiment 106 provides a composition for treatment of a subterraneanformation, the composition comprising:

a crosslinkable ampholyte polymer having about Z^(wt) wt % of anethylene repeating unit comprising the —C(O)NH₂ group, about N^(wt) wt %of an ethylene repeating unit comprising a —S(O)₂OR¹ group, and aboutM^(wt) wt % of an ethylene repeating unit comprising an —N⁺R² ₃X⁻ group,wherein

-   -   at each occurrence R¹ is independently selected from the group        consisting of —H and a counterion,    -   at each occurrence, R² is independently substituted or        unsubstituted (C₁-C₂₀)hydrocarbyl,    -   at each occurrence, X⁻ is independently a counterion,    -   the repeating units are in block, alternate, or random        configuration,    -   Z^(wt) is about 10% to about 70%, N^(wt) is about 1% to about        40%, and M^(wt) is about 20% to about 80%, and    -   the crosslinkable ampholyte polymer has a molecular weight of        about 100,000 g/mol to about 20,000,000 g/mol;

at least one crosslinker; and

a downhole fluid.

Embodiment 107 provides the composition of Embodiment 106, wherein thedownhole fluid comprises at least one of a drilling fluid, a fracturingfluid, a diverting fluid, and a lost circulation treatment fluid.

Embodiment 108 provides a crosslinked reaction product of thecomposition of Embodiment 106.

Embodiment 109 provides a composition for treatment of a subterraneanformation, the composition comprising:

a reaction product of a mixture comprising

-   -   a crosslinkable ampholyte polymer having about Z^(wt) wt % of an        ethylene repeating unit comprising the —C(O)NH₂ group, about        N^(wt) wt % of an ethylene repeating unit comprising a —S(O)₂OR¹        group, and about M^(wt) wt % of an ethylene repeating unit        comprising an —N⁺R² ₃X⁻ group, wherein        -   at each occurrence R¹ is independently selected from the            group consisting of —H and a counterion,        -   at each occurrence, R² is independently substituted or            unsubstituted (C₁-C₂₀)hydrocarbyl,        -   at each occurrence, X⁻ is independently a counterion,        -   the repeating units are in block, alternate, or random            configuration,        -   Z^(wt) is about 10% to about 70%, N^(wt) is about 1% to            about 40%, and M^(wt) is about 20% to about 80%, and        -   the crosslinkable ampholyte polymer has a molecular weight            of about 100,000 g/mol to about 20,000,000 g/mol; and    -   at least one crosslinker; and

a downhole fluid.

Embodiment 110 provides a system comprising:

the reaction product of the composition of Embodiment 109; and

a subterranean formation comprising the reaction product therein.

Embodiment 111 provides a composition for treatment of a subterraneanformation, the composition comprising:

a crosslinkable ampholyte polymer comprising repeating units having thestructure:

wherein

-   -   at each occurrence R¹ is independently selected from the group        consisting of —H and a counterion,    -   the repeating units are in a block, alternate, or random        configuration, and each repeating unit is independently in the        orientation shown or in the opposite orientation,    -   the crosslinkable ampholyte polymer has a molecular weight of        about 100,000 g/mol to about 20,000,000 g/mol, and    -   the crosslinkable ampholyte polymer has about 30 wt % to about        50 wt % of the ethylene repeating unit comprising the —C(O)NH₂        group, about 5 wt % to about 15 wt % of the ethylene repeating        unit comprising the —S(O)₂OR¹ group, and about 40 wt % to about        60 wt % of the ethylene repeating unit comprising the —N⁺R² ₃X⁻        group; and

a crosslinker comprising polyethyleneimine; and

a downhole fluid comprising at least one of a drilling fluid, afracturing fluid, a diverting fluid, and a lost circulation treatmentfluid, wherein about 0.001 wt % to about 30 v/v % of the composition isthe crosslinkable ampholyte polymer and the crosslinker.

Embodiment 112 provides a crosslinked reaction product of thecomposition of Embodiment 111.

Embodiment 113 provides a method of preparing a composition fortreatment of a subterranean formation, the method comprising:

forming a composition comprising

-   -   a crosslinkable ampholyte polymer comprising an ethylene        repeating unit comprising a —C(O)NH₂ group, an ethylene        repeating unit comprising an —S(O)₂OR¹ group, and an ethylene        repeating unit comprising an —N⁺R² ₃X⁻ group, wherein        -   at each occurrence, R¹ is independently selected from the            group consisting of —H and a counterion,        -   at each occurrence, R² is independently substituted or            unsubstituted (C₁-C₂₀)hydrocarbyl, and        -   at each occurrence, X⁻ is independently a counterion; and    -   at least one crosslinker.

Embodiment 114 provides the composition, apparatus, method, or system ofany one or any combination of Embodiments 1-113 optionally configuredsuch that all elements or options recited are available to use or selectfrom.

What is claimed is:
 1. A method of treating a subterranean formation,the method comprising: placing in the subterranean formation acomposition comprising a crosslinkable ampholyte polymer comprising anethylene repeating unit comprising a —C(O)NH₂ group, an ethylenerepeating unit comprising an —S(O)₂OR¹ group, and an ethylene repeatingunit comprising an —N⁺R² ₃X⁻ group, wherein at each occurrence, R¹ isindependently selected from the group consisting of —H and a counterion,at each occurrence, R² is independently substituted or unsubstituted(C₁-C₂₀)hydrocarbyl, and at each occurrence, X⁻ is independently acounterion; and at least one crosslinker; and crosslinking the polymerwith the crosslinker in the subterranean formation; wherein prior tocrosslinking of the crosslinkable ampholyte polymer the composition hasless friction in the subterranean formation than a correspondingcomposition that is the same as the composition comprising thecrosslinkable ampholyte polymer but that is free of the crosslinkableampholyte polymer, and the crosslinkable ampholyte polymer has aboutZ^(wt) wt % of the ethylene repeating unit comprising the —C(O)NH₂group, about N^(wt) wt % of the ethylene repeating unit comprising the—S(O)₂OR¹ group, and about M^(wt) wt % of the ethylene repeating unitcomprising the —N⁺R² ₃X⁻ group, wherein Z^(wt) is about 10% to about70%, N^(wt) is about 1% to about 40%, and M^(wt) is about 20% to about80%.
 2. The method of claim 1, wherein the composition further comprisesan aqueous liquid.
 3. The method of claim 2, wherein the aqueous liquidcomprises at least one of a drilling fluid, a fracturing fluid, adiverting fluid, and a lost circulation treatment fluid.
 4. The methodof claim 1, further comprising at least partially crosslinking thecrosslinkable ampholyte polymer to provide a crosslinked ampholytepolymer.
 5. The method of claim 1, wherein about 0.001 wt % to about 95wt % of the composition is the crosslinkable ampholyte polymer.
 6. Themethod of claim 1, wherein the crosslinkable ampholyte polymer has amolecular weight of about 100,000 g/mol to about 20,000,000 g/mol. 7.The method of claim 1, wherein the crosslinkable ampholyte polymercomprises repeating units having the structure:

wherein at each occurrence R³, R⁴, and R⁵ are each independentlyselected from the group consisting of —H and a substituted orunsubstituted C₁-C₅ hydrocarbyl, at each occurrence L¹, L², and L³ areeach independently selected from the group consisting of a bond and asubstituted or unsubstituted C₁-C₂₀ hydrocarbyl interrupted orterminated with 0, 1, 2, or 3 of at least one of —NR³—, —S—, and —O—,and the repeating units are in a block, alternate, or randomconfiguration, and each repeating unit is independently in theorientation shown or in the opposite orientation.
 8. The method of claim1, wherein the crosslinkable ampholyte polymer comprises repeating unitshaving the structure:

wherein the repeating units are in a block, alternate, or randomconfiguration, and each repeating unit is independently in theorientation shown or in the opposite orientation.
 9. The method of claim1, wherein the crosslinkable ampholyte polymer comprises repeating unitshaving the structure:

wherein the repeating units are in a block, alternate, or randomconfiguration, and each repeating unit is independently in theorientation shown or in the opposite orientation.
 10. The method ofclaim 1, wherein about 0.0001 wt % to about 80 wt % of the compositionis the crosslinker.
 11. The method of claim 1, wherein the crosslinkercomprises at least one of chromium, aluminum, antimony, zirconium,titanium, calcium, boron, iron, silicon, copper, zinc, magnesium, and anion thereof.
 12. The method of claim 1, wherein the crosslinkercomprises at least one of a poly(amino(C₂-C₁₀)hydrocarbylene)crosslinker and a (C₆-C₂₀)aryl alcohol-(C₁-C₂₀)aldehyde crosslinker. 13.The method of claim 1, wherein the crosslinker comprises at least one ofpolyethyleneimine, phenol-formaldehyde, and glyoxal.
 14. The method ofclaim 1, wherein the crosslinker comprises at least one of boric acid,borax, a borate, a (C₁-C₃₀)hydrocarbylboronic acid, a(C₁-C₃₀)hydrocarbyl ester of a (C₁-C₃₀)hydrocarbylboronic acid, a(C₁-C₃₀)hydrocarbylboronic acid-modified polyacrylamide, ferricchloride, disodium octaborate tetrahydrate, sodium metaborate, sodiumdiborate, sodium tetraborate, disodium tetraborate, a pentaborate,ulexite, colemanite, magnesium oxide, zirconium lactate, zirconiumtriethanol amine, zirconium lactate triethanolamine, zirconiumcarbonate, zirconium acetylacetonate, zirconium malate, zirconiumcitrate, zirconium diisopropylamine lactate, zirconium glycolate,zirconium triethanol amine glycolate, zirconium lactate glycolate,titanium lactate, titanium malate, titanium citrate, titanium ammoniumlactate, titanium triethanolamine, titanium acetylacetonate, aluminumlactate, and aluminum citrate.
 15. The method of claim 1, wherein thecomposition further comprises a secondary viscosifier.
 16. A systemconfigured to perform the method of claim 1, the system comprising: atubular disposed in the subterranean formation; and a pump configured topump the composition into the subterranean formation through thetubular.
 17. A method of treating a subterranean formation, the methodcomprising: placing in the subterranean formation a compositioncomprising a crosslinkable ampholyte polymer comprising repeating unitshaving the structure:

wherein at each occurrence, R¹ is independently selected from the groupconsisting of —H and a counterion, the repeating units are in a block,alternate, or random configuration, and each repeating unit isindependently in the orientation shown or in the opposite orientation,the crosslinkable ampholyte polymer has a molecular weight of about100,000 g/mol to about 20,000,000 g/mol, and the crosslinkable ampholytepolymer has about 30 wt % to about 50 wt % of the ethylene repeatingunit comprising the —C(O)NH₂ group, about 5 wt % to about 15 wt % of theethylene repeating unit comprising the —S(O)₂OR¹ group, and about 40 wt% to about 60 wt % of the ethylene repeating unit comprising the —N⁺R²₃X⁻ group; a crosslinker comprising polyethyleneimine; and a downholefluid comprising at least one of a drilling fluid, a fracturing fluid, adiverting fluid, and a lost circulation treatment fluid; andcrosslinking the polymer with the crosslinker in the subterraneanformation; wherein about 0.001 wt % to about 30 v/v % of the compositionis the crosslinkable ampholyte polymer and the crosslinker, and prior tocrosslinking between the crosslinkable ampholyte polymer and thecrosslinker the composition has less friction in the subterraneanformation than a corresponding composition that is the same as thecomposition comprising the crosslinkable ampholyte polymer but that isfree of the crosslinkable ampholyte polymer.